English for chemical and food engineers

English for Chemical and Food Engineers Xuan - Cuong Luu

Thi Hai - Yen Tran

Ho Chi Minh City - 2011

Hoang - Truc Phan

Preface ―The world is flat‖, nowadays, people from different country almost use English to communicate to each other and technical literatures are mostly written in this language. Unlike general English which plays important on grammar and new words, technical English requires very much technical knowledge to understand technical terminologies and processes.

In addition, the

meaning of words using in technical documents may be greatly different with that in general English, and to understand technical English some distinct techniques and skills may be required.

Improving English language skills through realistic, interesting reading is the vital aim of this book. We focus on combining the benefits of pleasure reading and direct instruction by relating to natural reading materials into the classroom. The book concludes to the research papers and journal, beside to related exercise in comprehension, vocabulary, and discussion.

This book might be essential to English learners who are engineers, scientists or university students in technical fields. Both a source of relevant vocabulary and a good example of technical writing style are mentioned within an interesting and familiar context.

The author welcomes both praise and constructive criticism which make the book useful for successful teaching and self-study purposes.

Book format This book consists of 4 parts, each with several units. The first part shows the reading kills, the searching information skills and the roles of keywords.

The second part supplies the fundamental knowledge in which the basic knowledge about chemistry (general chemistry, physical chemistry and organic chemistry) and chemical and food engineering (heat transfer, mass transfer and chemical process control) is presented. The third part is selective knowledge. Depending on students‘ field, they can see the suitable topics to increase their technical English. This part is written mainly for four majors including

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chemical process and equipment engineering, organic engineering, petrochemical & polymer engineering, environmental engineering and food engineering.

The book is enclosed with part four, in this part we introduced writing up research skills (abstract, introduction, materials/ experimental/theory, results and discussion, i.e.,) and one research on ―how to avoid the reviewer‘s axes‖.

How to use this book To instructor: This book can be used as textbook for class. To increase the efficiency of using this book, we recommend the ―Assessment for learning‖ method. This method of evaluation will enhance considerably the student‘s learning attitude. Based on this method the process of learning is evaluated instead of result of learning.

Activity Preparation

Content

Percent

Prepare one presentation about the topic for the next

10%

class. (group, home) Try to understand or to predict Translate all the readings for the next class (individual, the meaning of terminologies

home)

Test terminologies

Within 7-10 minutes, write down 20 new-words

10%

20%

learned in the previous time (individual, class) Class activity

Read and answer the question…(class)

10%

Final project

Test

50%

To Student: Remember that ―Practice makes perfect‖ and ―the roots of education are bitter but the fruit is sweet‖. Try to finish all the readings and assignments. Try to overcome the difficulties at the beginning and you will succeed.

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Acknowledges

This book could not be finished without various people help and advice. I am indebted to all of them. To enable to deal with ―real‖ texts from the ―real‖ scientific world, texts using in this book are mainly come from many textbooks, scientific articles; and hence our thanks are to those contributors.

In particular we would like to thank Nguyen Tat Thanh University for publishing our book and especially my colleges and friends who offered suggestions and gave valuable advice.

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Table of Content Preface ............................................................................................................................... i Acknowledges .................................................................................................................... iii Table of Content ................................................................................................................ iv Part 1.

Overview .............................................................................................................. 1

Unit 1.

How to Read a Scientific Research Papers ................................................... 1

Unit 2.

Searching Information Skills ........................................................................ 4

Part 2.

Fundamental Knowledge...................................................................................... 7

Unit 3.

General Chemistry ........................................................................................ 7

Unit 4.

Physical Chemistry ..................................................................................... 18

Unit 5.

Organic Chemistry ...................................................................................... 27

Unit 6.

Heat Transfer .............................................................................................. 35

Unit 7.

Mass Transfer.............................................................................................. 45

Unit 8.

Reaction and Reactor .................................................................................. 52

Unit 9.

Chemical Process control ............................................................................ 62

Part 3.

Selective Knowledge .......................................................................................... 72

Unit 10.

Distillation................................................................................................... 72

Unit 11.

Drying Process ............................................................................................ 78

Unit 12.

Crystallization ............................................................................................. 90

Unit 13.

Dyeing Process............................................................................................ 98

Unit 14.

Cosmetic Chemistry .................................................................................. 107

Unit 15.

Polymer Science........................................................................................ 114

Unit 16.

Polymer Processing ................................................................................... 122

Unit 17.

Fluid Catalytic Cracking ........................................................................... 129

Unit 18.

Reforming ................................................................................................. 138

Unit 19.

Wastewater ................................................................................................ 144

Unit 20.

Physicochemical Treatment Processes ..................................................... 151

Unit 21.

Biological Treatment Processes ................................................................ 161

Unit 22.

Browning Reaction ................................................................................... 171 iv

Unit 23.

Food Additives .......................................................................................... 176

Unit 24.

Beer Production ........................................................................................ 179

Unit 25.

Modified Atmosphere Packaging ............................................................. 185

Unit 26.

Emulsification and Homogenization......................................................... 189

Unit 27.

Biotechnology and Probiotic..................................................................... 192

Unit 28.

Recent Advances in Food Biotechnology Research ................................. 196

Unit 29.

Food Processing ........................................................................................ 200

Part 4.

Writing up Research and Scientific Paper........................................................ 209

Unit 30.

Writing up Research, Scientific paper ...................................................... 209

Unit 31.

Some Presentation skills ........................................................................... 216

Unit 32.

How to Avoid the Reviewer‘s Axes ......................................................... 218

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Part 1. Overview Unit 1.

How to Read a Scientific & Research papers

Objective: After reading this unit, you should able to Know some mistakes when reading scientific or research papesr. Know some knowhow/technichs to read research papers.

The readings are meant primarily for those learners who are interested in science and technology, or those who are more motivated to read scientific and technical literature than other genres (such as fiction, biography, history, news, etc.). Reading is not only a source of relevant vocabulary, but also a good example of technical writing style, and both vocabulary and style are provided within an interesting and familiar context. Here are some suggestions for you, the students that will help you enjoy reading in English and increase your reading comprehension. First, if applicable, think about ―how you read in your native language‖. Do you read silently or aloud? Do you know every word? What do you do when your encounter a word you do not know? If you do not understand every word, can you still understand what the text is about? As you read each reading selection in this book, rely as much as you can on what you already know. There are several sources of this background knowledge: your familiarity with the general topic, the title of the article, illustrations, the language you already know, and your personal experience can help you figure out what the author is trying to say. It is not necessary to know every word to understand the main message of the text. Good readers often skip words they do not know, but they are still able to understand the meaning of a sentence or the rest of the text. You may be able to figure out the meanings of many new words and expressions from the context.

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According to the English writing, the title of a text and the first paragraph tell the reader what the text is about. Use this structure to make sense of what you read. Use your existing knowledge with new information in the text to comprehend an article or story. For longer text, you may want to skim it first. To skim means to read or look at written material quickly in order to get the main idea. This will help you understand what you read. When you skim, take the following four steps: The first one is that reading the title and subtitle, look at illustrations and read illustration captions. This will help create a context for you.

Second, read the first one or two paragraphs to learn the general message of the article. Third, read the last paragraph for the author‘s summary or conclusions.

Finally, read the first and the last sentence of each paragraph or section to get some supporting information for the main message. Remember that in skimming, the goal is to grasp the main idea, details are not important. After skimming, read the entire article.

Read quickly, but comfortably. Do not worry if you do not understand a word or a phrase right away – just keep reading. The text that follows will usually explain the meanings of new items. Even native speakers who are good readers do not understand every detail when they read. They guest the meanings, and you should do the same. Words, phrases, grammatical forms and ideas are often repeated in the text, and this helps readers become more certain about new meanings. When you have finished a section of a reading, you can re-read previous words and phrases to check your understanding and to become more familiar with new expressions.

Example 1: Benefits: Golden Rice as a vitamin A supplement For the general population, Golden Rice can be beneficial because it serves as a source of supplementary vitamin A and carotenoids, vitamin A and

-carotene. High intake of specific vitamins and minerals, such as -carotene, have been linked with reducing risk of coronary artery

disease, specific cancers, and macular degeneration.

-carotene is an antioxidant; therefore, it

can help the protect the body from destructive free-radical reactions. Malnutrition is a global problem. As of 1995, 800 million people in the world have diets are inadequate in macronutrients (carbohydrates, lipid, and protein) and micronutrients (minerals and vitamins).

The major

deficiencies include vitamin A, iron, iodine, and vitamin E. Specifically, vitamin A deficiency

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causes blindness, premature death, and xerophthalmia (thickening on conjunctiva). Even people in the industrialized nations suffer from vitamin and mineral deficiencies due to poor diets. Therefore, a food staple such as rice, which is widely consumed globally, can serve as a means to address the vitamin A deficiency. Once the Golden Rice has been enhanced and developed, it can be cultivated, grown, and widely dispersed to eliminate vitamin A deficiency.

Example 2: A colourful and varied food Rice is rich in genetic diversity, with thousands of varieties grown throughout the world. In its natural unmilled state rice comes in many different colors, including brown, red, purple and even black. These colourful rice varieties are often prized for their health properties. Unmilled rice has a higher nutrient content than milled or polished white rice. For many cultures, rice forms an integral part of the culinary tradition. Different cultures have different preferences regarding the taste, texture, colour and stickiness of the rice varieties that they consume. For example, dry flaky rice is eaten in South Asia and the Middle East; moist sticky rices in Japan, Taiwan Province of China, the Republic of Korea, Egypt and northern China; and red rice in parts of southern India. Many countries have signature rice recipes, such as sushi, fried rice, curry, paella, risotto, pancit, and beans with rice. There are also many sweets and candies made from rice.

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Unit 2.

Searching information skills

Objective: After reading this unit, you should able to Know the importance of the keywords. Know how to find the desired information.

Roles of keywords Keywords are words or phrases that describe content. On the other hand, keywords can be defined as the specific terms used by person to search for something on the net. There are two different ways that show the role of keywords on searching information from the web. Keyword can be used as search terms for search engines and words that identify the content of the website. Whenever you search for something, you type keywords that tell the search engine what to search for. For example, if you are searching for food fermentation, you may enter "food fermentation" as your keywords. The search engine will then return web pages with content relevant to your search terms. The more specific keywords you use, the more specific and useful the results will be. Therefore, if you are searching for specific food fermentation, you may enter something like "wine fermentation" to get more accurate results. Especially, searching information in science is different from another field. You must link your keywords to related subjects so that you can get more results. For instance, for the keyword ―wine fermentation‖, you must think about that related subjects and choose the specific keyword which close to your search.

TASK 1: COMPREHENSION QUESTIONS Find the keywords in the text below:

Example 1: Biologically active components and nutraceuticals in the Monascus-fermented rice: a review

Monascus-fermented rice has traditionally beenused as a natural food colorant and food preservative of meat and fish for centuries. It has recently become a popular dietary supplement because of many of its bioactive constituents being discovered, including a series of active drug compounds, monacolins, indicated as the 3-hydroxy-3-methylglutaryl-coenzyme A reductase

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inhibitorsfor reducing serum cholesterol level. The controversy of its safety has been provoked because a mycotoxin, citrinin, is also produced along with the Monascus secondary metabolites by certain strains or under certain cultivation conditions. This review introduces the basic production process and addresses on the compounds with bioactive functions. Current advances in avoiding the harmful ingredient citrinin are also discussed. Example 2: Influence of antimicrobial packaging on kinetics of spoilage microbial growth in milk and orange juice The influence of antimicrobial packaging on the microbial growth in pasteurized milk and orange juice was examined. The liquid foods were located in contact with paperboard coated with nisin and/or chitosan in a binder of vinyl acetate ethylene copolymer at 3, 10 and 20 0C, and were measured for counts of aerobic bacteria and yeasts in the milk and orange juice, respectively. Paperboard coated only with plain binder was used as a control. The effect of antimicrobial packaging on the microbial growth was analyzed by using Barany‘s growth model. The paperboard coated with nisin and/or chitosan significantly improved the microbial stability of milk and orange juice at 3 and 100C, but not so noticeably at 200C. Of those tested, paperboards that included a combination of nisin and chitosan in the coating gave the highest microbial inhibition, and this was most apparent at 100C. The effectiveness of antimicrobial paperboard in suppressing the microbial growth was indicated by low maximum temperatures, extended lag time and reduced specific growth rates. Analysis by Ratkowsky equations showed that foods in contact with antimicrobial paperboards showed higher minimum growth temperatures and greater temperature dependence than did foods in contact with plain paper.

Example 3: In-situ Method for Analyzing the Long-Term Behavior of Particulate Metal Phases in Soils

Soils can act as a sink for anthropogenic and naturally released heavy metals. Among these are heavy metal oxides and sulfides, which are emitted e.g. by mining industry and metal smelting. The dissolution and transformation behavior of these heavy metal phases specifies their fate in the soil and determines whether the metals become bioavailable or could contaminate the groundwater. To gain more information about these dissolution reactions in soils, in-situ methods are needed. We present here a method to fix particulate metal phases on an inert support. This

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method allows us to expose and recover metal phases in the environment under controlled conditions.

Acrylic glass was chosen as inert polymer substrate for the heavy metal phases as it is stable to weathering. Epoxy resin was used as adhesive film between the acrylic glass support and the heavy metal coating. The fine-grained heavy metal phases are applied onto the epoxy resin using a dust spray gun. The heavy metal coated polymer platelets can be inserted in a controlled way into selected soil profiles and be recovered after definite time intervals. Qualifying and quantifying analysis can be carried out on every single polymer support.

Example 4. Diffusiophoresis of a nonuniformly charged sphere in an electrolyte solution

The diffusiophoresis of a rigid, nonuniformly charged spherical particle in an electrolyte solution is analyzed theoretically focusing on the influences of the thickness of double layer, the surface charge distribution, the effect of electrophoresis, and the effect of double-layer polarization. We show that the nonuniform charge distribution on the particle surface yields complicated effect of double-layer polarization, leading to interesting diffusiophoretic behaviors. For example, if the sign of the middle part of the particle is different from that of its left- and right-hand parts, then depending upon the charge density and the fraction of the middle part, the particle can move either to the high-concentration side or to the low-concentration side. Both the diffusiophoretic velocity and its direction can be manipulated by the distribution of the surface charge density. In particular, if the electrophoresis effect is significant, then those properties are governed by the averaged surface charge density of the particle. A dipole like particle, where its left- (right-) hand half is negatively (positively) charged, always migrates toward the low-concentration (left-hand) side, that is, it has a negative diffusiophoretic velocity. In addition, that diffusiophoretic velocity has a negative local minimum as the thickness of double layer varies.

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Part 2. Fundamental Knowledge Unit 3.

General Chemistry

Objective: After reading this unit, you should able to Know what general chemistry is. Know how to divide general chemistry. Know some definitions relating substances and properties.

READING 1 Chemistry is the science that describes matter – its properties, the changes it undergoes, and the energy changes that accompany those processes. Matter includes everything that is tangible, from our bodies and the stuff of our everyday lives to the grandest objects in the universe. Some call chemistry the central science. It rests on the foundation of mathematics and physics and in turn underlies the life sciences – biology and medicine. To understand living systems fully, we must first understand the chemical reactions and chemical influences that operate within them. The chemicals of our bodies profoundly affect even the personal world of our thoughts and emotions.

No one can be expert in all aspects of such a broad science as chemistry. Sometimes we arbitrarily divide the study of chemistry into various branches. Carbon is very versatile in its bonding and behavior and is a key element in many substances that are essential to life. All living matter contains carbon combined with hydrogen. The chemistry of compounds of carbon and hydrogen is called organic chemistry. (In the early days of chemistry, living matter and inanimate matter were believed to be entirely different. We now know that many of the compounds found in living matter can be made from nonliving, or ―inorganic,‖ sources. Thus, the terms ―organic‖ and ―inorganic‖ have different meanings than they did originally.) The study of substances that do not contain carbon combined with hydrogen is called inorganic chemistry. The branch of chemistry that is concerned with the detection or identification of substances present in a sample (qualitative analysis) or with the amount of each that is present (quantitative analysis) is called analytical chemistry. Physical chemistry applies the mathematical theories and methods of physics to the properties of matter and to the study of chemical processes and the accompanying energy changes. As

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its name suggests, biochemistry is the study of the chemistry of processes in living organisms. Such divisions are arbitrary, and most chemical studies involve more than one of these traditional areas of chemistry. The principles you will learn in a general chemistry course are the foundation of all branches of chemistry.

TASK 1: VOCABULARY CHECK Find the words in the text which mean:

1. that can be clearly seen to exist 2. a living thing 3. a series of things that are done in order to achieve a particular result 4. most important 5. not alive in the way that people, animals and plants are 6. the process of recognizing that sth exists 7. a principle, an idea or a fact that sth is based on and that it grows from 8. having many different uses

TASK 2: COMPREHENSION QUESTIONS Answer the questions below

1. Why is chemistry called the central science? ............................................................................................................................................................. 2. What is the general characteristic of carbon? ............................................................................................................................................................. 3. What is the difference between qualitative analysis and quantitative analysis? .............................................................................................................................................................

READING 2

Matter is anything that has mass and occupies space. Mass is a measure of the quantity of matter in a sample of any material. The more massive an object is, the more force is required to put it in motion. All bodies consist of matter. Our senses of sight and touch usually tell us that an object occupies space. In the case of colorless, odorless, tasteless gases (such as air), our senses may fail us.

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Mixtures are combinations of two or more pure substances in which each substance retains its own composition and properties. Almost every sample of matter that we ordinarily encounter is a mixture. The most easily recognized type of mixture is one in which different portions of the sample have recognizably different properties. Such a mixture, which is not uniform throughout, is called heterogeneous. Examples include mixtures of salt and charcoal (in which two components with different colors can be distinguished readily from each other by sight), foggy air (which includes a suspended mist of water droplets), and vegetable soup. Another kind of mixture has uniform properties throughout; such a mixture is described as a homogeneous mixture and is also called a solution. Examples include salt water; some alloys, which are homogeneous mixtures of metals in the solid state; and air (free of particulate matter or mists). Air is a mixture of gases. It is mainly nitrogen, oxygen, argon, carbon dioxide, and water vapor. There are only trace amounts of other substances in the atmosphere.

An important characteristic of all mixtures is that they can have variable composition. (For instance, we can make an infinite number of different mixtures of salt and sugar by varying the relative amounts of the two components used.) Consequently, repeating the same experiment on mixtures from different sources may give different results, whereas the same treatment of a pure sample will always give the same results. When the distinction between homogeneous mixtures and pure substances was realized and methods were developed (in the late 1700s) for separating mixtures and studying pure substances, consistent results could be obtained. This resulted in reproducible chemical properties, which formed the basis of real progress in the development of chemical theory. Mixtures can be separated by physical means because each component retains its properties. For example, a mixture of salt and water can be separated by evaporating the water and leaving the solid salt behind. To separate a mixture of sand and salt, we could treat it with water to dissolve the salt, collect the sand by filtration, and then evaporate the water to reclaim the solid salt. Very fine iron powder can be mixed with powdered sulfur to give what appears to the naked eye to be a homogeneous mixture of the two. Separation of the components of this mixture is easy, however. The iron may be removed by a magnet, or the sulfur may be dissolved in carbon disulfide, which does not dissolve iron. In any mixture, the composition can be varied and each component of the mixture retains its own properties. Imagine that we have a sample of muddy river water (a heterogeneous mixture). We might first separate the suspended dirt from the liquid by filtration. Then we could remove dissolved air by warming the water. Dissolved solids might be removed by cooling the sample until some of it freezes, pouring off the liquid, and then melting the ice. Other dissolved components might be separated by distillation or other methods. Eventually we would obtain a sample of pure water that could not be further separated by any physical separation methods. No matter what the original source of the impure water—the ocean, the Mississippi River, a can of tomato juice, and so on—water samples obtained by

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purification all have identical composition, and, under identical conditions, they all have identical properties. Any such sample is called a substance, or sometimes a pure substance.

TASK 3: TRUE OR FALSE Decide whether the following statements are true (T) or false (F).

1. Matter is anything made of atoms and molecules. 2. There is chemical bonding between substances in a mixture. 3. A mixture consists of two or more different substances that are mixed but not chemically combined together. 4. A mixture where one substance dissolves in another is called heterogeneous. 5. Air is heterogeneous mixture. 6. Homogeneous mixtures have only one phase, or have a uniform appearance throughout, and any portion of the sample has the same properties and composition.

7. The difference between heterogeneous and homogeneous mixtures is the degree at which the materials are mixed together. 8. A homogeneous mixture is a mixture where the components of the mixture are not uniform or have localized regions with different properties. 9. A separation process is used to transform a mixture of substances into two or more distinct products.

TASK 4: SUMMARY Make a summary of how to separate the components of muddy river water by drawing a diagram.

READING 3 A substance cannot be further broken down or purified by physical means. A substance is matter of a particular kind. Each substance has its own characteristic properties that are different from the set of properties of any other substance. Now suppose we decompose some water by passing electricity through it. (An electrolysis process is a chemical reaction.) We find that the water is converted into two simpler substances, hydrogen and oxygen; more significantly, hydrogen and oxygen are always present in the same ratio by mass, 11.1% to 88.9%. These observations allow us to identify water as a compound.

A compound is a substance that can be decomposed by chemical means into simpler substances, always in the same ratio by mass. As we continue this process, starting with any substance, we eventually reach a

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stage at which the new substances formed cannot be further broken down by chemical means. The substances at the end of this chain are called elements. An element is a substance that cannot be decomposed into, for instance, neither of the two gases obtained by the electrolysis of water – hydrogen and oxygen – can be further decomposed, so we know that they are elements. As another illustration, pure calcium carbonate (a white solid present in limestone and seashells) can be broken down by heating to give another white solid (call it A) and a gas (call it B) in the mass ratio 56.0 : 44.0. This observation tells us that calcium carbonate is a compound. The white solid A obtained from calcium carbonate can be further broken down into a solid and a gas in a definite ratio by mass, 71.5 : 28.5. But neither of these can be further decomposed, so they must be elements. The gas is identical to the oxygen obtained from the electrolysis of water; the solid is a metallic element called calcium. Similarly, the gas B, originally obtained from calcium carbonate, can be decomposed into two elements, carbon and oxygen, in a fixed mass ratio, 27.3 : 72.7. This sequence illustrates that a compound can be broken apart into simpler substances at a fixed mass ratio; those simpler substances may be either elements or simpler compounds.

TASK 5: GAP FILLING Complete the diagram with appropriate phrases or sentences below

1. Variable composition 2. Components are distinguishable. 3. can be decomposed into simpler substances by chemical changes, always in a definite ratio 4. fixed composition 5. Properties do not vary. 6. have same composition throughout 7. Mixtures of different compositions may have widely different properties. 8. cannot be decomposed into simpler substances by chemical changes 9. cannot be separated into simpler substances by physical methods 10. Components retain their characteristic properties. 11. everything that has mass 12. do not have same composition throughout 13. Components are indistinguishable. 14. can only be changed in identity and properties by chemical methods 15. may be separated into pure substances by physical methods

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MATTER -

MIXTURES

PURE SUBSTANCES

-

-

Physical changes

HOMOGENE OUS MIXTURES -

HETEROGENE OUS MIXTURES -

COMPOUN DS -

ELEMEN TS -

Chemical changes

Figure 1.1. Chemical changes

READING 4

Table 1. 1

Some characteristics of Solids, Liquids, and Gases Solids

Liquids

1. Have define shape (resist 1. Have no define shape deformation) 2. Are nearly incompressible 3. Usually have higher density than liquids 4. Are not fluid 5. Diffuse only very slowly through solids

6. Have an ordered arrangement of particles

(assume shapes of containers) 2. Have define volume (are

Gases 1.

Have no difine shape (fill container completely)

2. Are compressible 3. Have low density

only very slightly

4. Are fluid

compressible)

5. Diffuse rapidly

3. Have high density

6. Consist of extremely

4. Are fluid

disordered particle with much

5. Diffuse through other liquids

empty space between them;

6. Consist of disordered

particles have rapid, random

that are very close

cluster of particles that are

together; particles have

quite close together;

vibrational motion only

particles have random motion in three dimensions

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motion in three dimensions.

TASK 5: GAP FILLING Complete the sentences with appropriate words or phrases (1) ………exists in three physical states: solids, liquids, and gases. In the solid state H2O is known as ice, in the liquid state it is called water, and in the gaseous state it is known as steam or water vapor. Most, but not all, (2) ………can exist in all three states. Most solids change to liquids and most liquids change to gases as they are (3) ………. Liquids and gases are known as (4) ………because they flow freely. Solids and liquids are referred to as (5) ……… because they have much higher densities than gases. Solids and liquids are many times denser than gases. The molecules must be very far apart in gases and much closer together in liquids and solids. For example, the volume of one mole of liquid water is about 18 milliliters, whereas one mole of steam occupies about 30,600 milliliters at 100°C and atmospheric pressure. Gases are easily (6) ………, and they completely fill any container in which they are present. This tells us that the molecules in a gas are far apart relative to their sizes and that (7) ……… among them are weak. The possibilities for interaction among gaseous molecules would be minimal (because they are so far apart) were it not for their rapid (8) ………. All substances that are gases at room temperature may be liquefied by cooling and compressing them. Volatile liquids are easily converted to (9) ……… at room temperature or slightly above. The term vapor refers to a gas that is formed by evaporation of a liquid or sublimation of a solid. We often use this term when some of the liquid or solid remains in contact with the gas.

TASK 6: TRUE OR FALSE Decide whether the following statements are true (T) or false (F).

1. Matter can be classified into three states. 2. In the solid state, substances are rigid and have definite shapes. 3. Volumes of solids vary much with changes in temperature and pressure. 4. In the liquid state, the individual particles are confined to a given volume. 5. A liquid flows and assumes the shape of its container up to the volume of the liquid. 6. Gases are very hard to compress. 7. Gases are much more dense than liquids and solids. 8. Liquids occupy all parts of any vessel in which they are confined. 9. Gases are capable of infinite expansion and are compressed easily.

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READING 5 To distinguish among samples of different kinds of matter, we determine and compare their properties. We recognize different kinds of matter by their properties, which are broadly classified into chemical properties and physical properties. Chemical properties are exhibited by matter as it undergoes changes in composition. These properties of substances are related to the kinds of chemical changes that the substances undergo. For instance, we have already described the combination of metallic magnesium with gaseous oxygen to form magnesium oxide, a white powder. A chemical property of magnesium is that it can combine with oxygen, releasing energy in the process. A chemical property of oxygen is that it can combine with magnesium. All substances also exhibit physical properties that can be observed in the absence of any change in composition. Color, density, hardness, melting point, boiling point, and electrical and thermal conductivities are physical properties. Some physical properties of a substance depend on the conditions, such as temperature and pressure, under which they are measured. For instance, water is a solid (ice) at low temperatures but is a liquid at higher temperatures. At still higher temperatures, it is a gas (steam). As water is converted from one state to another, its composition is constant. Its chemical properties change very little. On the other hand, the physical properties of ice, liquid water, and steam are different. Properties of matter can be further classified according to whether or not they depend on the amount of substance present. The volume and the mass of a sample depend on, and are directly proportional to, the amount of matter in that sample. Such properties, which depend on the amount of material examined, are called extensive properties. By contrast, the color and the melting point of a substance are the same for a small sample and for a large one. Properties such as these, which are independent of the amount of material examined, are called intensive properties. All chemical properties are intensive properties. TASK 7: MULTIPLE CHOICE

1. That magnesium can combine with oxygen is a) b) c) d)

an extensive property an intensive property a chemical property both b & c are correct

2. Density is

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a) b) c) d)

a chemical & intensive property a physical & intensive property a chemical & extensive property a physical & extensive property

3. The state of water depends on a) b) c) d)

mass volume temperature boiling point

TASK 8: CLASSIFICATION Classify each of the following as an extensive or intensive property.

1. The volume of beer in a mug 2. The percentage of alcohol in the beer 3. The number of calories of energy you derive from eating a banana 4. The number of calories of energy made available to your body when you consume 10.0 g of sugar 5. The mass of iron present in your blood 6. The mass of iron present in 5 ml of your blood 7. The electrical resistance of a piece of 22-gauge copper wire 8. The electrical resistance of a 1-km length of 22-gauge copper wire 9. The pressure of air in a bicycle tire

TASK 9: How to find good keywords

Find the keywords in reading paragraphs 3 and 5

TASK 10: Summary

In about 5 sentences, summarize the main idea in paragraphs 3 and 5

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TASK 11: Glossary

Search your knowledge, look up your dictionary, internet or ask your instructor to clarify the definition and Vietnamese meaning of the following terminologies. No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Terminology alloys analytical chemistry bonding characteristic composition compounds decompose dissolve electrolysis element element evaporate extensive properties filtration heterogeneous homogeneous intensive properties living organisms matter Mixtures muddy physical chemistry powder process property pure substances purification reactions solution state sublimation

Definition

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Vietnamese

32 33 34

substance vapor volatile

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Unit 4.

Physical Chemistry

Objective: After reading this unit, you should able to Know what physical chemistry is. Know what adsorption process is. Know the physical chemistry keywords.

READING 1

Physical chemistry is the study of the physical basis of chemical systems and processes. It is concerned with the measurement, description, and prediction of the characteristics of chemical systems and their interactions with each other with respect to the transfer of mass and energy. There are some important areas of its study. 1. Chemical thermodynamics deals with the transfer of energy in chemical changes and seeks to characterize the equilibrium state of chemical systems. 2. Chemical kinetics deals with the rate and mechanism of chemical changes. 3. Structure of matter is a broad area of experimental and theoretical description of the properties of matter at the atomic and molecular level. 4. Quantum theory explains the nature of chemical bonding while the spectra of atoms and molecules are explained by quantum mechanics. 5. The discipline that allows us to ring our knowledge of molecular structure to bear on the problems of equilibrium and kinetics is found in the study of statistical mechanics.

TASK 1: MATCHING Match a word or phrase in A with its definition in B

A

B

1) Chemical changes

a) condition in which no change occurs

2) Equilibrium

b) strong attractive force that holds together atoms in molecules

3) Structure of matter

c) arrangement and interaction of the particles of a substance

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4) Quantum mechanics

d) modern theory of matter

5) Chemical bonding

e) process in which one set of reactants is transformed in to a new set of products

TASK 2: MAIN TOPICS Complete the passages with the appropriate phrases describing the major branches of physical chemistry 1. …………… which revolutionized physics in the early part of this century, is required for an understanding of chemistry. The spectra of atoms and molecules are explained by quantum mechanics, and their theoretical treatment yields quantities of importance in various areas of physical chemistry. The nature of chemical bonding is explained by quantum theory. 2. …………… has been developed to provide an interpretation of the properties of matter in terms of the properties of molecules, atoms, ions, and electrons. Both thermodynamic properties and kinetic properties of matter may be calculated using statistical mechanics, provided that certain information about molecules is known from spectroscopic or other measurements.

3. …………… involves the time factor and is concerned with molecules and mechanisms. Many reactions in organic chemistry, inorganic chemistry, and many industrial processes, the products are not in the state of equilibrium, and the yields are controlled more by the relative rates of reaction than by thermodynamics. Chemical kinetics is based on almost all of physical chemistry. Kinetic theory is based upon certain assumptions about molecules. The results of kinetic theory based upon classical physics have been very useful but come into direct contradiction with certain experimental results such as the dependence of heat capacity upon temperature. However, classical kinetic theory is very helpful in understanding the results of both thermodynamics sand chemical kinetics. It is necessary to obtain a completely satisfactory theory. 4. …………… can be determined from X-ray diffraction, electron diffraction, and molecular spectra. Information on molecular structure is of importance for understanding chemical reactions and for calculating thermodynamic and kinetic behavior. Certain types of chemical behavior can be predicted when the molecular structure is known.

5. …………… is one of the most powerful tools of physical chemistry. It provides exact relations between energy and properties of systems without any information about molecules or mechanisms of

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processes. Thermodynamics applies to systems at equilibrium and is concerned only with initial and final states. It has nothing to do with time. Thermodynamics provides an answer to the question, ―How far will this particular reaction go before equilibrium is reaches?‖

READING 2

To be technically effective in a commercial separation process, whether this be a bulk separation or a purification, an adsorbent material must have a high internal volume which is accessible to the components being removed from the fluid. Such a highly porous solid may be carbonaceous or inorganic in nature, synthetic or naturally occurring, and in certain circumstances may have true molecular sieving properties. The adsorbent must also have good mechanical properties such as strength and resistance to attrition and it must have good kinetic properties, that is, it must be capable of transferring adsorbing molecules rapidly to the adsorption sites. In most applications the adsorbent must be regenerated after use and therefore it is desirable that regeneration can be carried out efficiently and without damage to mechanical and adsorptive properties. The raw materials and methods for producing adsorbents must ultimately be inexpensive for adsorption to compete successfully on economic grounds with alternative separation processes.

The high internal surface area of an adsorbent creates the high capacity needed for a successful separation or purification process. Adsorbents can be made with internal surface areas which range from about 100 m2/g to over 3000 m2/g. For practical applications, however, the range is normally restricted to about 300 – 1200 m2/g. For most adsorbents the internal surface area is created from pores of various size. Many adsorbent materials, such as carbons, silica gels and aluminas, are amorphous and contain complex networks of interconnected micropores, mesopores and macropores. In contrast, in zeolitic adsorbents the pores or channels have precise dimensions although a macroporous structure is created when pellets are manufactured from the zeolite crystals by the addition of a binder. Fluid molecules which are to be adsorbed on the internal surface must first pass through the fluid film which is external to the adsorbent particle, thence through the macroporous structure into the micropores where the bulk of the molecules are adsorbed.

Adsorbent particles have a finite capacity for fluid phase molecules and therefore extended contact with a feedstock will ultimately lead to the creation of a thermodynamic equilibrium between the solid and fluid phases. At this equilibrium condition the rates of adsorption and desorption are equal and the net loading

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on the solid cannot increase further. It now becomes necessary either to regenerate the adsorbent or to dispose of it. For those applications in which it is economically favorable to regenerate the adsorbent it is necessary to devise processes in which the regeneration method can be incorporated.

TASK 3: COMPREHENSION QUESTIONS Answer the questions below

1. What are the required properties of an adsorbent material to be effective in a separate process?

........................................................................................................................................................................................ 2. Why is it necessary that adsorbents be regenerated?

........................................................................................................................................................................................ 3. What is the internal surface area range of adsorbents in practical applications?

........................................................................................................................................................................................ 4. In what case are the rates of adsorption and desorption equal?

........................................................................................................................................................................................ 5. How many types of pores are there in silica gels?

.........................................................................................................................................................................

TASK 4: GAP FILLING Complete the sentences with appropriate words or phrases The (1) ………. properties of activated carbons are essentially due to their surface area, universal (2) ………. effect, highly microporous structure, and a high degree of surface reactivity. The availability of favorable pore size makes the internal surface accessible and enhances the adsorption rate. The most widely used activated carbons have a specific (3) ………. of 800 to 1500 m2/g. This surface area is contained predominantly within micropores that have effective diameters smaller than 2 nm. In fact, a particle of active carbon consists of a network of pores that have been classified into micropores (diameters < 2 nm), mesoporous (diameter between 2 and 50 nm) and macropores (diam. > 50 nm). The (4) ………. do not contribute significantly toward surface areas but act as conduits for the passage of the adsorbate into the interior (5) ………. and the (6) ………. surface where most of the adsorption takes place. Although the adsorption capacity of active carbons is determined by their physical or porous structure, it is strongly influenced by the chemical structure of their surface. In graphites, for example, which have a highly ordered crystalline structure, the adsorption capacity is determined by the dispersion component of London forces. In the case of active carbons, however, the (7) ………. ordering of the aromatic sheets causes a variation in the arrangement of electron clouds in the carbon skeleton, which

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results in the creation of unpaired electrons and incompletely saturated valencies that would undoubtedly influence the adsorption behavior. In addition (8), ………. are generally associated with oxygen and hydrogen, which are present in the form of carbonoxygen and carbon-hydrogen surface groups. These surface groups are bonded at the edges of the aromatic sheets. Because these edges constitute the main adsorption surface, these surface groups profoundly influence the adsorption behavior of active carbons. Besides, the active carbon surface has (9) ………. in the form of edges, dislocations and discontinuities that determine the chemical reactions and the catalytic properties of active carbon.

READING 3

Adsorption decolorization of sugar solutions is the final step in the purification process. The sugar juices are first cleared of the impurities by processes such as clarification (liming), saturation, affination, centrifugation, and filtration. These treatments help the activated carbon to retain its adsorption capacity. The activated carbon treatment is the last stage of the purification process before the sugar juices are boiled to produce white mother liquor from which white sugar can be obtained. In the manufacture of beet sugar, activated carbon is used for decolorizing thin juice, thick juice, and liquors.

Sugar solutions contain different types of coloring matter. They can be classified into (i) caramels (i.e., nitrogen-free coloring substances formed by the partial thermal decomposition of sugars containing phenolic and quinoid groups, (ii) melanoidines (i.e., nitrogen containing coloring substances formed by reactions of reducing sugars with amino compounds, and (iii) iron containing polyphenolic complexes. These coloring substances are present both as dissociated and nondissociated compounds, but frequently the anion types are prevalent. The substances with molecular masses between 8000 and 15000 occurring in colloidal form produce the most intense color in sugar solutions.

The decolorizing capacity of an active carbon depends upon the physical structure that involves pore size and the chemical structure that includes the acidity or alkalinity of the carbon surface as also on the nature of the coloring matter present in the sugar solution. Within the range of pH values met with in the sugar manufacturing process, lowering of the pH value usually improves decolorization. A pH of 4.5 is optimum for decolorization, but it cannot be used because inversion of sugar may take place. It is advisable to reduce the alkalinity of sugar juices by sulfitation before treating with active carbons. Sulfitation improves decolorization by active carbons. The decolorizing activity of an active carbon is measured in terms of the molasses number.

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The treatment of sugar solutions with active carbons only slightly increases the purity of the solution, usually 0.1 percent at most, but gives the solution better optical appearance. It also markedly enhances the processing properties. For example, by removing surface active agents and colloidal substances, the surface tension of the solution is enhanced and its viscosity is decreased. These changes result in higher rates of sucrose crystallization and improve the separation of syrup from crystals during centrifugation.

TASK 5: TRUE OR FALSE Decide whether the following statements are true (T) or false (F).

1. Sugar solutions contain various kinds of dissociated colorants. 2. The physical structure of activated carbon determines its decolorizing capacity. 3. The sugar juices are cleared of the impurities before activated carbon treatment so that the activated carbon retains its adsorption capacity. 4. The decolorization of sugar solutions works best at pH of 4.5. 5. The purity of sugar solutions is greatly improved after the activated carbon treatment.

TASK 6: MATCHING Match a word or phrase in A with its definition in B

1) Filtration

a) the process by which crystals are obtained from a saturated solution of a substance, by allowing the solvent to evaporate slowly

2) Centrifugation

b) changing from an adsorbed state on a surface to a gaseous or liquid state

3) Desorption

c) the process of removing undesirable chemicals, materials, and biological contaminants from contaminated mixture

4) Purification

d) the process whereby fluids pass through a filter or a filtering medium

5) Crystallization

e) the process of separating substances of different densities by the use of a centrifuge

READING 4

Decolorization of sugar solutions using powdered active carbons can be carried out by two methods: contact batch method and the continuous layer filtration method. There is a third method, which is a

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combination of both the methods. The contact batch method is a batch process in that a given amount (5 to 10 kg.m–3 of syrup) of the activated carbon is added to the sugar syrup placed in a container. The resulting suspension is kept at a temperature of 80 to 90oC for about 20 min, which is sufficient time to attain adsorption equilibrium. The suspension is then pumped into filter presses to remove the active carbon. During filtration the thickness of the filter cake (carbon bed) increases to 25 to 35 mm, and this results in an increase in the hydrodynamic resistance from 2 x 105 to 4 x 105 Pa. Therefore, the pressure during filtration has to be increased from 2 atm to 4 atm. About 600 kg of carbon is collected in 1m 3 of filter volume. When the filter press is full, the active carbon is sweetened off by washing with 6 to 9 times its weight of water. The active carbon is then removed and the filter press assembled again. Continuous layer filtration involves filtering the sugar syrup through a layer of activated carbon. Several types of filters are used, such as pressure leaf filters with metal frames on which a filter cloth that may be cotton, polyamide, or wire mesh is fixed; rotary leaf filters or bed filters in which the filtering medium is a ceramic or sintered plate, wire mesh, or finely perforated metal plate. The latter filters are usually coated with a layer of filter aid that may be a diatomaceous earth. A suspension of active carbon in water or liquor is passed through the filter until a uniform layer of active carbon bed 10 to 15 mm thick builds up. The filter is then ready for filtration of the liquor that must flow to the filter at a uniform rate to avoid breaking the layer. It is worth mentioning here that each of the two methods described above requires different activated carbons with different properties. For example, in the contact batch method, the active carbons used should have good filtering properties, because the flow rates here are about 10 times higher than in the continuous layer filtration method, although the decolorizing ability of the carbon may be lower. This method is very flexible, and dosage of the carbon can be easily varied depending upon the color of the syrup or juice. The continuous layer filtration, on the other hand, requires an active carbon with high decolorizing properties. In this case, the filtering properties of the active carbons are not important. Another important difference between the two methods is the consumption of the active carbon that amounts to 0.3 to 1.0% of refined sugar in the contact batch method and about 10 times smaller (i.e., 0.05 to 0.1%) in the continuous layer filtration method. However, the quality of the active carbon in the latter method has to be higher. The choice between the two methods depends upon the size of the plant and the economic considerations.

The combined method utilizes the advantages of the above two methods. The filter is precoated with a layer of fresh active carbon, and a dose of active carbon can be added to the sugar solution. The decolorized solution is refiltered through a bed of diatomaceous earth, which serves to remove active carbon that might have passed through a damaged filter, cloth, or channel in the filter cake. Without refiltration, the final product may have a gray color.

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TASK 7: SUMMARY Compare the contact batch method and the continuous layer filtration method in terms of principle, the quality and the consumption of activated carbon.

TASK 9: How to find good keywords Find the keywords in reading paragraphs 3 and 4 TASK 10: Summary In about 5 sentences, summarize the main idea in paragraphs 3 and 5

TASK 11: Glossary

Search your knowledge, look up your dictionary, internet or ask your instructor to clarify the definition and Vietnamese meaning of the following terminologies. . No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Terminology thermodynamics equilibrium state kinetics mechanism experimental theoretical atomic molecular quantum mechanics statistical mechanics rates of reaction diffraction mechanisms resistance

Definition

adsorb adsorbent

adsorbate regenerate amorphous

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Vietnamese

20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

35 36 37

micropores mesopores macropores pellets particle adsorption desorption activated carbons porous effective diameters valencies saturation affination centrifugation acidity alkalinity complexes colloid

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Unit 5.

Organic Chemistry

Objective: After reading this unit, you should able to Know what organic chemistry is. Know how to understand organic chemistry. Know the organic chemistry keywords.

READING 1

Organic chemistry is the study of those carbon-containing molecules known as organic compounds, which are based upon long chains or rings of carbon atoms. Over 6 million organic compounds are known today and the possibility exists for countless more to be discovered and synthesized. Organic chemists determine the structure of organic molecules, study their various reactions and develop procedures for the synthesis of organic compounds. Organic chemists have had a profound effect on modern life: It has improved natural materials and it has synthesized natural and artificial materials that have, in turn, improved health, increased comfort, and added to the convenience of nearly every product manufactured today.

TASK 1: COMPREHENSION QUESTIONS Answer the questions below.

1. What are organic compounds?

............................................................................................................................................................................................... 2. What is the job of an organic chemist?

............................................................................................................................................................................................... 3. Give an example to illustrate that organic chemists have had a profound effect on modern life.

...............................................................................................................................................................................................

READING 2 All organic compounds are primarily divided into two large groups: acyclic compounds – with an open chain and cyclic compounds – with a closed chain.

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Acyclic compounds are also called fatty or aliphatic (from a Greek word meaning fat) since fats and fatty acids belong to this class. These compounds may have a ―normal‖ structure, i.e., have an unbranched skeleton similar to the skeleton of normal pentane or a branched skeleton (with various degree of branching), such as isopentane.

Cyclic compounds are classified in isocyclic, in which there is a cyclic grouping consisting of several carbon atoms closed into a ring and heterocyclic, in which the ring includes one or more atoms other than carbon (heteroatoms). A special position among such cyclic compounds is occupied by so-called aromatic compounds, six-membered rings containing alternating three single and three double carbon-carbon bonds or bonds between a carbon atom and a heteroatom.

TASK 2: TRUE OR FALSE Decide whether the following statements are true (T) or false (F).

1.

Organic compounds are classified according to their structural formulas, the spatial arrangement of the atoms.

2.

The word ―fat‖ is derived from the Greek language.

3.

Acyclic compounds can be either saturated or unsaturated fatty compounds.

4.

An aliphatic compound of ―normal structure‖ is one which has a branched-chain structure.

5.

Heterocyclic compounds consist of hydrocarbons arranged in a ring.

6.

Isocyclic compounds with alternating double carbon-carbon bonds are aromatic compounds.

TASK 3: GAP FILLING Complete the passage with appropriate words below

chains

aromatic heterocyclic

ring

aliphatic hydrogen atoms

structure

hydrocarbons heterocycles

1. Organic compounds are classified according to their (1)……………., this classification being based on the character of the carbon skeleton of (2)………….., i.e., the sequence of carbon atoms linked to one

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another. Compounds that contain atoms other than carbon are regarded as derivatives of hydrocarbons, in which (3)………. are replaced by such atoms called heteroatoms. An exception is made for such structure in which the heteroatom closes the (4)………………. Of carbon atoms into a (5)………….. Such cyclic or ring compounds are classified as a special class of compounds termed (6)……….. 2. Some of the classes of substances studied in organic chemistry include (7)……….. compounds, chains of carbon which may be modified by functional groups; (8)………. Hydrocarbons compounds containing one or more benzene rings; (9)…………….. compounds, which include non-carbon atoms as parts of a ring structure and polymers, which are long (10)………….of repeating groups or so-called monomers.

READING 3

Organic chemistry is a broad field which intersects with such diverse areas as biology, medicine and pharmacology, polymer technology, agriculture, and petroleum engineering. At the heart of organic chemistry are fundamental concepts of molecular structure and reactivity of carbon-containing compounds. The purpose of this text is to explore this central core, which is concerned with how the structures of organic compounds are related to reactivity. Reactivity, in turn, determines the methods that can be used for synthesis. Understanding of structure, reactivity, and synthesis can be used within organic chemistry or applied to other fields, such as those named above, which require contributions from organic chemistry. Structure includes the description of bonding in organic molecules and the methods for determining, analyzing, and predicting molecular structure. Dynamic aspects of structure, such as conformational equilibria, are also included. Stereochemistry is also a crucial aspect of structure in organic chemistry. Reactivity pertains to the aspects of a given structure that determine its chemical transformations. Is the molecule electron-rich or electron-poor? Is it easily reduced or oxidized? What is the distribution of the most reactive electrons? Which bonds are weakest and therefore most likely to engage in reactions? Unlike structure, which is an inherent property of the molecule, reactivity usually describes an interaction with other molecules. Understanding reactivity includes describing the mechanisms, that is the stepwise process by which reactions occur. Reactivity also encompasses the stereochemical aspects of the transformation. Synthesis encompasses those activities which are directed toward finding methods that convert existing substances in different compounds. Synthesis involves the control of reactivity to achieve specified transformations. It involves the choice of reagents, catalysts, and reaction conditions that will accomplish a given transformation within the required parameters. In various circumstances, the limiting parameters might include yield, purity of product, stereochemical control, availability or cost of reagents, or safety and environmental consequences. Structure, reactivity, and

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synthesis are all interrelated. Synthesis is built on knowledge of both structure and reactivity, and understanding reactivity ultimately rests on detailed knowledge about molecular structure. A firm grounding in the principles of structure and chemical bonding is therefore and essential starting point for fuller appreciation of reactivity and synthesis. We will discuss the ideas that have proven most useful to organic chemists for describing and organizing facts, concepts, and theories about the structure of organic molecules.

TASK 4: MATCHING Match a word or phrase in A with its definition in B

1) Structure determination

a) how to find out how these molecules react with each other and how to predict their reactions

2) Theoretical organic

b) how to understand those structures in terms of atoms and the

chemistry

electrons that bind them together

3) Reaction mechanisms

c) how to design new molecules - and then make them

4) Synthesis

d) how to find out what Nature does and how the structures of biologically active molecules are related to what they do

5) Biological chemistry

e) how to find out the structures of new compounds even if they are available only in invisibly small amounts

TASK 5: GAP FILLING Complete the passage with appropriate words below atom(s)

chemical reaction(s) static

molecule(s)

mechanism dynamic

structure(s)

elements bond(s)

1. To understand organic chemistry you must be familiar with two languages. One, which we have concentrated on so far, is the (1)……….. and representation of (2)…………... The second is the description of the reaction (3) ………. in terms of curly arrows and that is what we are about to start. The first is (4) …….. and the second (5) ………. The creation of new (2)………. is the special concern of chemistry and an interest in the mechanism of (6)………… is the special concern of organic chemistry.

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2. Organic chemistry concerns itself with the way in which these atoms are bonded together into stable molecular (1) ……….., and the way in which these (2)………………… change in the course of (6)…………. 3. Unlike most other elements, carbon forms strong (7)……….to other carbon (8)………. and to a wide variety of other (9) ………. Chains and rings of carbon (8)…………..can be built up to form an endless variety of (2)……... It is this diversity of carbon compounds that provides the basis for life on Earth.

TASK 6: MAIN IDEA Which is not the main idea of the passage? 1. Organic chemistry is a field which relates to many areas, for example, biology, medicine, pharmacology, etc. 2. Structure, reactivity, and synthesis are closely connected. 3. Organic chemists must know how to describe and organize facts, concepts, and theories about the structure of organic molecules. 4. Stereochemistry is an important aspect of structure. 5. Reactivity describes the step-by-step pathway from reactants to products

TASK 7: SUMMARY Make a summary of the interrelation of structure, reactivity, and synthesis by drawing a diagram, a table, or a map.

READING 4

The reaction of methane with chlorine produces a mixture of chlorinated products, whose composition depends on the amount of chlorine added and also on the reaction conditions. Either light or heat is needed for the reaction to take place at a useful rate. When chlorine is added to methane, the first reaction is

This reaction may continue; heat or light is needed for each step:

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This sequence raises several questions about the chlorination of methane. Why is heat or light needed for the reaction to go? Why do we get a mixture of products? Is there any way to modify the reaction to get just one pure product? Are the observed products formed because they are the most stable products possible? Or are they favored because they are formed faster than any other products? The answers to these questions involve three aspects of the reaction: the mechanism, the thermodynamics, and the kinetics. 1. The mechanism is the complete, step-by-step description of exactly which bonds break and which bonds form in what order to give the observed products. 2. Thermodynamics is the study of the energy changes that accompany chemical and physical transformations. It allows us to compare the stability of reactants and products and predict which compounds are favored by the equilibrium. 3. Kinetics is the study of reaction rates, determining which products are formed fastest. Kinetics also helps to predict how the rate will change if we change the reaction conditions.

We will use the chlorination of methane to show how we study a reaction. Before we can propose a detailed mechanism for the chlorination, we must learn everything we can about how the reaction works and what factors affect the reaction rate and the product distribution. A careful study of the chlorination of methane has established three important characteristics: 1. The chlorination does not occur at room temperature in the absence of light. The reaction begins when light falls on the mixture or when it is heated. Thus, we know this reaction requires some form of energy to initiate it. 2. The most effective wavelength of light is a blue color that is strongly absorbed by chlorine gas. This finding implies that light is absorbed by the chlorine molecule, activating chlorine so that it initiates the reaction with methane. 3. The light-initiated reaction has a high quantum yield. This means that many molecules of the product are formed for every photon of light absorbed. Our mechanism must explain how hundreds of individual reactions of methane with chlorine result from the absorption of a single photon by a single molecule of chlorine.

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TASK 8: VOCABULARY CHECK Find the words in the text which mean:

1. a combination of different things 2. a unit of electromagnetic energy 3. the total amount of something produced 4. the quality or state of being steady and not changing in any way 5. a measurement of the speed at which something happens

TASK 9: COMPREHENSION QUESTIONS Answer the questions below 4. What factors does the number of the chlorinated products depend on?

........................................................................................................................................................................................ 5. What are the three aspects of the reaction of methane with chlorine?

........................................................................................................................................................................................ 6. What are the advantages of understanding the thermodynamics of a reaction?

........................................................................................................................................................................................ 7. How can we know that energy can help initiate the chlorination of methane?

........................................................................................................................................................................................ 8. What is a reaction with high quantum yield?

........................................................................................................................................................................................

TASK 10: How to find good keywords Find the keywords in reading paragraphs 3 and 4 TASK 11: Summary In about 5 sentences, summarize the main idea in paragraphs 3 and 4

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TASK 12: Glossary

Search your knowledge, look up your dictionary, internet or ask your instructor to clarify the definition and Vietnamese meaning of the following terminologies. No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Terminology structure synthesis acyclic compounds cyclic compounds aliphatic fatty acids Skeleton or chain branched skeleton isocyclic heterocyclic heteroatoms aromatic medicine pharmacology reactivity conformational reduced oxidized stereochemical transformation parameters yield purity rings chlorination

Definition

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Vietnamese

Unit 6.

Heat Transfer

Objective: After reading this unit, you should able to Know what heat transfer is. Know the mechanism of heat transfer process. Know several heat exchanger types.

Reading 1. Thermodynamics and Heat transfer

We all know from the experience that a cold canned drink left in a room warms up and a warm canned drink left in a refrigerator cools down. This is accomplished by the transfer of energy from the warm medium to the cold one. The energy transfer is always from the higher temperature medium to the lower temperature one, and the energy transfer stops when the two medium reach the same temperature.

The basic requirement for heat transfer is the presence of a temperature difference. There can be no net transfer between two mediums that are at the same temperature. The temperature difference is the driving force for heat transfer, just as the voltage difference is the driving force for electric current flow and pressure difference is the driving force for fluid flow. The rate of heat transfer in a certain direction depends on the magnitude of the temperature gradient (the temperature difference per unit length or the rate of change of (temperature) in that direction. The larger the temperature gradient, the higher the rate of heat transfer. Heat can be transfer in three different modes: conduction, convection and radiation. All modes of heat transfer require the existence of a temperature difference, and all modes are from the hightemperature medium to a lower-temperature one.

TASK 1: COMPREHENSION QUESTIONS Answer the questions below

1. What is temperature gradient? ............................................................................................................................................................. 2. What is the driving force for heat transfer? .............................................................................................................................................................

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3. Sometimes, heat can be transferred from lower medium temperature to higher temperature one. That clause is true or false?

................................................................................................................................................ 4. How many modes can heat transfer occur?

................................................................................................................................................

Reading 2: Heat conduction

Conduction is the transfer of energy from the more energetic particles of a substance to the adjacent less energetic ones as a result of interactions between the particles. Conduction can take place in solids, liquid, or gases. In gases and liquids, conduction is due to the collisions and diffusion of the molecules during their random motion. In solids, it is due to the combination of vibrations of the molecules in a lattice and the energy transport by free electrons. A cold canned drink in a warm room, for example, eventually warms up the room temperature as a result of heat transfer from the room to the drink through the aluminum can by conduction.

The rate of heat conduction through a medium depends on the geometry of the medium, its thickness, and the material of the medium, as well as the temperature difference across the medium. We know that wrapping a hot water tank with glass wool (an insulating material) reduces the rate of heat loss from the tank. The thicker the insulation is, the smaller the heat loss. We also know that a hot water tank will lose heat at a higher rate when the temperature of the room housing the tank will lose heat at a higher rate when the temperature of the room housing the tank is lower. Further, the larger the tanks, the larger the surface are and thus the rate of heat loss.

TASK 2: COMPREHENSION QUESTIONS Answer the questions below 1. When can particle be called ―energetic particle‖? ............................................................................................................................................................. 2. Can you give some examples about conduction in solids, liquids and gases? ............................................................................................................................................................. 3. ―In gases and liquids, conduction is due to the collisions and diffusion of the molecules during their random motion. In solids, it is due to the combination of vibrations of the molecules in a lattice and the energy transport by free electrons.‖ – why?

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............................................................................................................................................................. 4. Have you ever seen glass fiber? Could you tell where insulating materials can be used? .............................................................................................................................................................

Reading 3. Heat convection

Convection is the mode of energy transfer between a solid surface and the adjacent liquid or gas that is in motion, and it involves the combined effects of conduction and fluid motion. The faster the fluid motion, the greater the convection heat transfer is. In the absence of any bulk fluid motion, heat transfer between a solid surface and the adjacent fluid is by pure conduction. The presence of bulk motion of the fluid enhances the heat transfer between the solid surface and the fluid, but is also complicates and determination of heat transfer rate. Sometimes, the terminology ―advection‖ can be used to refer the heat transfer only by fluid motion; and hence, convecion is a combination of conduction and advection.

Convection is called forced convection if the fluid is forced to flow over the surface by external means such as a fan, pump, or the wind. In contrast, convection is called natural (or free) convection if the fluid motion is caused by buoyancy forces that the induced by density differences due to the variation of temperature in the fluid. For example, in the absence of a fan, heat transfer from the surface of the hot block will be by natural convection since any motion in the air in this case will be due to the rise of the warmer (and thus lighter) air near the surface and the fall of the cooler (and thus heavier) air to fill its place. Heat transfer between the block and the surrounding air will be by conduction if the temperature difference between the air and block is not large enough to overcome the resistance of air to movement and thus to initiate natural convection currents.

Heat transfer processes that involve change of phase of a fluid are also considered to be convection because of the fluid motion induced during the process, such as the rise of the vapor bubbles during boiling or the fall of the liquid droplets during condensation. Despite the complexity of convection, the rate of convection heat transfer is observed to be proportional to the temperature difference, and is conveniently expressed by Newton‘s law of cooling as

Qconv

hAs (Ts T )

(6.1)

Where h is the convection heat transfer coefficient in W/m2.oC, As is the surface area through which convection heat transfer takes place, Ts is the surface temperature, and T is the temperature of the fluid sufficiently far from the surface. Note that at the surface, the fluid temperature equals the surface temperature of the solid.

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The convection heat transfer coefficient h is not a property of the fluid. It is an experimentally determined parameter whose value depends on all the variables in influencing convection such as the surfce geometry, the nature of the fluid motion, the properties of the fluid, and the bulk fluid velocity.

TASK 3. COMPREHENSION QUESTIONS Answer the questions below

1. What is convection/ natural convection/ force convection? ............................................................................................................................................................. 2. What is advection? ............................................................................................................................................................. 3. Can you explain in your own words Newton‘s law of cooling? ............................................................................................................................................................. 4. Can you explain how ―bulk fluid velocity‖ can affect the heat transfer rate?

................................................................................................................................................

Reading 4. Radiation

Radiation is the energy emitted by matter in the form of electromagnetic waves (or photons) as a result of the changes in the electronic configurations of the atoms or molecules. Unlike conduction and convection, the transfer of energy by radiation does not require the presence of an intervening medium. In fact, energy transfer by radiation is fastest (at the speed of light) and it suffers no attenuation in a vacuum. This is how the energy of the sun reaches the earth. In heat transfer studies we are interested in thermal radiation, which is the form of radiation emitted by bodies because of their temperature. It differs from other forms of electromagnetic radiation such as X-rays, gamma rays, microwaves, radio waves, and television waves that are not related to temperature. All bodies at a temperature above absolute zero emit thermal radiation. Radiation is a volumetric phenomenon, and all solids, liquids, and gases emit, absorb, or transmit radiation to varying degrees. However, radiation is usually considered to be a surface phenomenon for solids that are opaque to thermal radiation such as metals, wood and rocks since the radiation emitted by the interior regions of such material can never reach the surface, and the radiation incident on such bodies is usually absorbed within a few microns from the surface. The maximum rate of radiation that can be emitted from a surface at an absolute temperature Ts (in K or R) is given by the Stefan-Boltzmann law as:

38

Qemit ,max Where

AsTs4

(6.2)

= 5.67 * 10-8 W/m2. K4 is the stefan-Boltzmannn constant. The idealized surface that emits

radiation at this maximum rate is called a blackbody, and the radiation emitted by a black-body is called blackbody radiation. The radiation emitted by all real surfaces is less than the radiation emitted by a blackbody at the same temperature, and is express as

Qemit ,max

Where

AsTs4

(6.3)

is the emissivity of the surface. The property emissivity, whose value is in the range 0< 0.6 then the waste is fairly biodegradable and can be effectively treated biologically. If BOD/COD ratio is between 0.3 and 0.6, then seeding is required to treat it biologically. If BOD/COD is 100 - 100 mm) and settleable (> 100 µm). The type of treatment selected depends on the size of particles present in the wastewater. In practice, treatment efficiency also depends on particle size. Solids of the size that are visible to the naked eye can be separated either by settling under the influence of gravity or by flotation, depending on the relative densities of solids and water. They may also be easily separated by filtration. However, very fine particles of a colloidal nature (called colloids, size < 1 µm) which have high stability are significant pollutants. The reason for this stability is that these particles have electrostatic surface charges of the same sign (usually negative). This means that repulsive forces are created between them, preventing their aggregation and subsequent settling. It has therefore proved impossible to separate them by settling or flotation. It is not possible to separate these solids by filtration because they pass through any filter. However, separation by physico-chemical treatments is possible. Physico-chemical treatment of wastewater focuses primarily on the separation of colloidal particles. This is achieved through the addition of chemicals (called coagulants and flocculants). These change the physical state of the colloids allowing them to remain in an indefinitely stable form and therefore form into particles or flocs with settling properties.

TASK 1. COMPREHENSION QUESTIONS Answer the questions below.

1. According to the reading, how many types of particles can be classified? What are they?

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.................................................................................................................................................................... 2. How can the coarse particle be separated from the wastewater? .................................................................................................................................................................... 3. Why is colloid difficult to settle? .................................................................................................................................................................... 4. Can we use membrane to remove colloid from water? .................................................................................................................................................................... 5. To remove colloid, coagulants or flocculants are added to the solution, please tell the reasons

......................................................................................................................................................

Reading 2.

1. Screening The very first unit operation in waste water treatment is screening. Screening is an essential step in wastewater treatment for the removal of bigger suspended and floating solids which would otherwise damage equipment, interfere with the operation of treatment units or equipments. Screens are used ahead of pumping stations, meters and as a first step in all treatment works. A screen is a device with opening generally of uniform size for removing bigger suspended or floating matter in wastewater. The screening element consists of parallel bars, rods gratings or wiremeshes or perforated plates and the openings may be of any shape although generally they are circular or rectangular, depending on the size of the opening screens classified as coarse, medium or fine.

2. Grit chamber

Grit chambers are designed to remove grit, consisting of sand, gravel, cinders or other heavy solid materials that have specific gravities much greater than those of the organic putrescible solids in the wastewater. Most of the substances of grit are abrasive in nature and will cause accelerated wear on pumps and sludge handling equipment with which it comes in contact. Grit deposits are not biodegradable and occupy large space in sludge digesters. It is therefore desirable to separate grit deposits from he organic suspended solids.

Grit chamber is assumed to be one in which particles settle as individual entities, and where there is no significant interaction with the neighboring particles, which is known as free settling or discrete settling or

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type I settling. Grit removal facilities basically consist of an enlarged channel area where reduced flow velocities allow grit to settle out. Mechanical scrapers remove the deposited grit. For proper functioning of the grit chamber, the velocity through the grit chamber should not be allowed to change inspite of the change in flow. One of the most satisfactory type of automatic velocity control is achieved by providing a proportional Weir at the outlet. The shape of the opening between the plates of a proportional weir is made in such a way that the chamber depth will vary directly as the discharge, as a result of which the chamber velocity will remain constant for all flow conditions.

TASK 2: True or False Decide whether the following statements are true (T) or false (F).

1. Grid chambers which remove, for example, sand, gravel and heavy metal are normally placed before the screen. 2. Materials removing by grid chamber are oftenly bigger than that removing by screen. 3. Screens are positioned behind pump to ensure that no coarse materials which affect the later process can pass. 4. Most of the substances of grit are chemically corrosive in nature and will damage pump. 5. We can use microbial to treat the substances removing by grit. 6. The chamber velocity can vary with the fluctuations of wastewater load.

Reading 3. 3. Flow equalizaion

Flow equalization is used to minimize te variability of water and wastewater flow rates and composition. Each unit operation is a treatment train is designed for specific wastewater characteristics. Improved efficiency and control are possible when all unit operations are carried out at uniform flow conditions. If there exists a wide variation in flow composition over time, the treatment efficiency of the overall process performance may degrade severely. These variations in flow composition could be due to many reasons, including the cyclic nature of industrial processes, the sudden occurrence of storm water events, and seasonal variations. To dampen these variations, equalization basins are provided at the beginning of the treatment train. The influent water with varying flow composition enters this basin first before it is allowed to go through the rest of treatment process. Equalization tanks serve many purposes. Many processes use equalization basins to accumulate and consolidate smaller volumes of wastewater such that

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full scale batch reactors can be operated. Other processes incorporate equalization basins in continuous treatment systems to equalize the waste flow so that the effluent at the downstream end can be discharged at a uniform rate.

4. Neutralization

Neutralization is a common practice in wastewater treatment and waste stabilization. If a waste stream is found to be hazardous because of corrosivity, neutralization is the primary treatment used. Moreover, neutralization is used as a pretreatment system before a variety of biological, chemical and physical treatment processes. Since many chemical treatment processes, such as metal precipitation, coagulation, phosphorus precipitation, and water softening are pH dependent, the pH of these processes is adjusted to achieve maximum process efficiency. Furthermore, the pH of the effluent wastewater from different is industrial activities also requires adjustment prior to its discharge into receiving water bodies, the US EPA has set pH standards for different types of water; for example, the pH range required to protect marine aquatic life is 5-9.

Neutralization is the process of adjusting the pH of water through the addition of an acid or a base, depending on the target pH and process requirements. Some processes such as boiler operations and drinking water standards need neutral water at a p of 7. Water and wastewater is generally considered adequately neutralized if (1) its damage to metals, concrete, or other materials is minimal; (2) it has little effect on fish and aquatic life; (3) it has no effect on biological matter (i.e., biological treatment systems).

TASK 3. COMPREHENSION QUESTIONS Answer the questions below.

1. What is the role of flow equalization? .................................................................................................................................................................... 2. Name some reasons causing the change in flow composition? ....................................................................................................................................................................

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3. Why equalization tank help full scale batch reactors can be operated? .................................................................................................................................................................... 4. Which characteristics of watewater we should use neutralization? .................................................................................................................................................................... 5. Which chemical treatment processes are effective with appropriate pH value? .................................................................................................................................................................... 7. To not damage marine aquatic life, which range of pH value of the discharged wastewater? .................................................................................................................................................................... 8. In which cases, water and wastewater is generally considered adequately neutralized?

...................................................................................................................................................... Reading 4. 5. Coagulation and Flocculation Coagulation and flocculation constitute the backbone processes in most water and advanced wastewater treatment plants. Their objective is to enhance the separation of particulate species in downstream processes such as sedimentation and filtration. Colloidal particles and other finely divided matter are brought together and agglomerated to form larger size particles that can subsequently be removed in a more efficient fashion. The traditional use of coagulation has been primarily for the removal of turbidity from potable water. However, more recently, coagulation has been shown to be an effective process for the removal of many other contaminants that can be adsorbed by colloids such as metals, toxic organic matter, viruses, and radionuclides. The researchers divided the coagulation process into three distinct and sequential steps: 1. coagulant formation 2. Particle destabilization 3. Inter-particle collisions

The first two steps are usually fast and take place in a rapid-mixing tank. The third step, inter-particle collisions, is a slower process that is achieved by fluid flow and slow mixing. This is the process that causes the agglomeration of particles and it takes place in the flocculation tank. Coagulation is usually achieved through the addition of inorganic coagulants such as aluminum or iron-based salts, and/or synthetic organic polymers commonly known as polyelectrolyte.

Properties of Colloidal Systems

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Colloids are very small particles that have extremely large surface area. Colloidal particles are larger than atoms and ions ut are small enough that they are usually not visible to the naked eye. They range in size from 0.001 to 10 micom resulting in a very small ratio of mass to surface area. The consequence of this smallness in size and mass and largeness in surface area is that the colloidal suspensions 1. Gravitational effects are negligible, and 2. Surface phenomenon predominates.

Because of their tremendous surface, colloidal particles have the tendency to adsorb various ions from the surrounding medium that impart to the colloids and electrostatic charge relative to the bulk of surrounding water. The developed electrostatic repulsive forces prevent the colloids from coming together and, consequently, contribute to their dispersion and stability.

Following the first step of coagulation, a second process called flocculation occurs. Flocculation, a gentle mixing stage, increases the particle size from submicroscopic microfloc to visible suspended particles. The microflocs are brought into contact with each other through the process of slow mixing. Collisions of the microfloc particles cause them to bond to produce larger, visible flocs called pinflocs. The floc size continues to build through additional collisions and interaction with inorganic polymers formed by the coagulant or with organic polymers added. Macroflocs are formed. High molecular weight polymers, called coagulant aids, may be added during this step to help bridge, bind, and strengthen the floc, add weight, and increase settling rate. Once the floc has reached it optimum size and strength, the water is ready for the sedimentation processes.

TASK 4. MULTIPLE CHOICE QUESTION Answer the questions below. 1. The coagulation process can be classified into…….steps. a. 1

b. 2

c. 3

d. 4

2. Which step should be took place in slow mixing condition? a. coagulant formation

b.Inter-particle collisions

c. Particle destabilization

d. b&c

3. Colloids are very small particles that have a. very large surface

b. very large volume

c.

very

large

volume/surface 4. Colloidal suspensions are stable because

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ratio d.

very

large

surface/volume

ratio

a.

of the electrostatic repulsive force between the particles.

b. colloids are too small to collide with each other. c. collision between the colloids are prevented by ions in the solution. d. Adsorbed ions on the colloidal surface prevent colloids stick together. 5. Flocculation process occurs through sequential steps a.

Microfloc - pinfloc  macrofloc  sediment.

b. Pinfloc microfloc macrofloc  sediment. c. Sediment microfloc

pinfloc  macrofloc.

d. Pinfloc mirofloc sediment

 macrofloc

6. Coagulant aids are added in flocculation process in order to: a.

Generate bridge between the microflocs or pinfloc.

b. Stick small flocs together. c. Prevent macroflocs from breaking d. a, b and c are right.

Reading 5. Chemical Precipitation Precipitation is a chemical unit process in which undesirable soluble metallic ions and certain anions are removed from water or wastewater by conversion to an insoluble form. It is a commonly used treatment technique for removal of heavy metals, phosphorus, and hardness. The procedure involves alteration of the ionic equilibrium to produce insoluble precipitates that can be easily removed by sedimentation. Chemical precipitation is always followed by a solids separation operation that may include coagulation and/or sedimentation, or filtration to remove the precipitates. The process can be preceded by chemical reduction in order to change the characteristics of the metal ions to a form that can be precipitated.

Precipitation processes should be distinguished from coagulation and flocculation. Coagulation is the removal of finely divided non-settleable solid particles, especially colloids, by aggregation into larger particles through the destabilization of the electric double layer (4). Flocculation is the formation of yet larger particles by the formation of bridges between coagulated particles through the adsorption of large polymer molecules and by other forces. Both coagulation and flocculation, which often occur together, result in particles that can be removed by sedimentation or filtration. Coagulation and flocculation occur subsequent to and concomitant with the precipitation processes as it is usually applied in waste treatment Sedimentation

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Sedimentation is defined as a unit operation in which suspended particles are separated from a suspension by gravitational settling. The terms clarification and thickening of sludge apply to the same unit operation. Coagulation, which is discussed before, involves the addition of chemicals to induce faster aggregation and settling of initially finely divided suspended and colloidal particles. The objective of sedimentation is to remove settleable particles from suspensions either with or without the addition of chemicals. When no chemicals are added to the process, it is called plain sedimentation. Plain sedimentation is usually employed in wastewater treatment, whereas in water- treatment plants, sedimentation, in most cases, is preceded by chemical coagulation. Sedimentation is also employed, to a limited scale, in separating particulates from air streams.

TASK 5. COMPREHENSION QUESTIONS Answer the questions below.

1. What is the principle of precipitation process? .................................................................................................................................................................... 2. Chemical precipitation should be placed before coagulation and/or sedimentation, or filtration unit. Why? .................................................................................................................................................................... 3. Sometime, the metal ions need be change the oxidation state. What are the reasons? .................................................................................................................................................................... 4. What is the driving force of sedimentation phenomenon? .................................................................................................................................................................... 5. Whether particle size removing by coagulation or flocculation is larger that that by sedimentation?

......................................................................................................................................................

Reading 6. Dissolved Air Floatation Process

Dissolved Air Flotation (DAF) is the process of removing suspended solids, oils and other contaminants via the use of air bubble flotation. Air is dissolved into water, mixed with the wastestream and released from solution while in intimate contact with the contaminants. Air bubbles form, attach to the solids, increase their buoyancy and float the solids to the water's surface. A percentage of the clean effluent is recycled and super-saturated with air, mixed with the wastewater influent and injected into the DAF separation chamber.

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The dissolved air comes out of solution, producing millions of microscopic bubbles. These bubbles attach to the solids and float them to the surface where they are mechanically skimmed and removed from the tank. Dissolved air flotation systems are designed to remove fats, oils & grease (FOG), suspended solids, food/animal production/processing wastes, industrial wastes, hydrocarbon oils/emulsions and many other contaminants. Clarification rates as high as 97% or more can be achieved using our dissolved air flotation systems. Chemical pre-treatment can often help to improve the performance of contaminant removal.

TASK 6. COMPREHENSION QUESTIONS Answer the questions below

1. What does DAF stand for? .................................................................................................................................................................... 2. In DAF technology, should the waste collector be placed at the bottom of the tank or at the surface water? Why? .................................................................................................................................................................... 3. In your opinion, whether the big bubble gas size or small bubble size is good? ....................................................................................................................................................................

TASK 7: How to find good keywords Find the keywords in reading paragraphs 4 and 5 TASK 8: Summary In about 5 sentences, summarize the main idea in paragraphs 4 and 5

TASK 10: Glossary

Search your knowledge, look up your dictionary, internet or ask your instructor to clarify the definition and Vietnamese meaning of the following terminologies. No 1 2

Terminology abrasive accumulate

Definition

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Vietnamese

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

agglomerate aggregation aggregation basin coagulation consolidate contaminant corrosivity deposit destabilization equalization filtration flocculation flocs flotation flotation grit chamber insoluble ludge Neutralization pollutant precipitation pump removal repulsive Screening sedimentation settle supracolloidal

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Unit 21.

Biological Treatment Processes

Objective: After reading this unit, you should able to Know what biological treatment is. Know what steps occur in biological process. Know how many types of biological treatment processes are. Know the biological treatment process keywords.

Reading 1. Primary treatment

Primary treatment is a physico-chemical treatment that removes the pollutants which settle or float. Secondary treatment is the treatment that follows the primary treatment which delivers an effluent that got rid of most of its impurities and after which the effluent can be safely disposed of into natural courses of water. Biological treatment is the mostly favored secondary treatment and for that the wastewater must be predominantly BIODEGRADABLE i.e. BOD/COD > 0.6 Domestic sewage definitely is biodegradable. Microorganisms under favorable conditions remove dissolved organic solids and colloidal solids and get themselves removed. A Large number of organisms in a small reactor decompose the organic matter in a smaller interval of time under ideal conditions operating with high efficiency. Carbonaceous BOD removal is the biological conversion of the carbonaceous organic matter in wastewater to cell tissue and various gaseous end products. Substrate is the term used to denote the organic matter or nutrients that are converted during biological treatment. Carbonaceous organic matter in wastewater is referred to as the substrate that is converted during biological treatment.

In the removal of carbonaceous BOD, the coagulation of non-settleable colloidal solids and the stabilization of organic matter are accomplished biologically using a variety of microorganisms, principally bacteria. The microorganisms are used to convert the colloidal and dissolved carbonaceous organic matter to various gases and into cell tissue. Because cell tissue has a specific gravity slightly greater than that of water, the resulting tissue can be removed from the treated liquid by gravity settling. The major biological processes used for wastewater treatment are classified into four major groups as aerobic processes, anoxic processes, anaerobic processes and a combination of the aerobic, anoxic or

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anaerobic processes. Bacteria are classified into two major groups as heterotrophic or autotrophic based on their source of nutrients. Heterotrophic, sometimes referred to as saprophytes use organic matter as both an energy and a carbon source for synthesis. These bacteria are further subdivided into three groups, aerobic, anaerobic facultative aerobes and facultative anaerobes based on their action toward free oxygen. Autotrophic bacteria oxidize inorganic compounds for energy and use carbon dioxide as a carbon source. Aerobes require free dissolved oxygen in decomposing organic matter to gain energy for growth and multiplication.

Aerobic reactions: Organics + Oxygen

 CO2

+

H2O

+ Energy

Anaerobic Reactions:

Anaerobes oxidize organics in the complete absence of dissolved oxygen by using oxygen bound in other compounds, such as nitrate and sulphate. Organics + NO3-  CO2 2-

Organics + SO4

 CO2

 N2

+ Energy

 H2S + Energy

The individual processes are further subdivided depending on whether the treatment accomplished is suspended-growth systems, attached-growth systems or combinations thereof. Suspended growth processes are the biological treatment processes in which the microorganisms responsible for the conversion of the organic matter or other constituents in the wastewater to gases and cell tissue are maintained in suspension within the liquid. Attached-growth processes are the biological treatment in which the microorganisms responsible for the conversion of the organic matter or other constituents in the wastewater topazes and cell tissue are attached to some inert medium, such as rocks, slag or specially designed ceramic or plastic materials. Attached-growth processes are also known as fixed-film processes.

TASK 1. COMPREHENSION QUESTIONS Answer the questions below

1. Is biological treatment processes placed before physicochemical treatment processes? .................................................................................................................................................................... 2. Which parameter of wastewater we should know before choosing biological treatment method?

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.................................................................................................................................................................... 3. In biological method, how can dissolved organic solids and colloidal solids be removed? .................................................................................................................................................................... 4. How many major biological processes are suggested in the reading? What are they? .................................................................................................................................................................... 5. Based on their source of nutrients, how many kinds of bacteria? .................................................................................................................................................................... 6. What are the attached-growth processes? .................................................................................................................................................................... 7. What are the suspended growth processes?

......................................................................................................................................................

Reading 2. Trickling Filter

Trickling filters (TFs) are used to remove organic matter from wastewater. The TF is an aerobic treatment system that utilizes microorganisms attached to a medium to remove organic matter from wastewater. This type of system is common to a number of technologies such as rotating biological contactors and packed bed reactors (biotowers). These systems are known as attached- growth processes. In contrast, systems in which microorganisms are sustained in a liquid medium are known as suspended-growth processes. Trickling filter consists of a bed of highly permeable media to which microorganisms are attached and through which wastewater is percolated or trickled.

TFs enable organic material in the wastewater to be adsorbed by a population of microorganisms (aerobic, anaerobic, and facultative bacteria, fungi, algae, and protozoa) attached to the medium as a biological film or slime layer (approximately 0.1 to 0.2 mm thick). As the wastewater comes in contact with the medium, microorganisms of the wastewater gradually attach themselves to the rock, slag, or plastic surface to form a zoogleal film. The organic material is then decomposed by the aerobic microorganisms in the outer part of the biological layer.

As the layer thickness through microbial growth, oxygen cannot penetrate through the entire thickness of the medium, and anaerobic organisms develop within. As the biological film continues to grow, the microorganisms near the free surface lose their ability to cling to the medium which is away may get detached. The detached slime layer goes down along with wastewater. This process is known as

163

sloughing. Sloughing is primarily a function of organic and hydraulic loading of the filter. The sloughed solids are transported to the secondary clarifier.

TASK 2: True or False Decide whether the following statements are true (T) or false (F).

1. The TF is an aerobic treatment system that utilizes microorganisms attached to a medium to remove organic matter from wastewater. 2. The media of TF to which microorganisms are attached is very permeable. 3. Aerobic microorganisms in all biological layer take part in decomposing organic materials. 4. Sloughing is the process in which detached biological layer goes down along with wastewater. 5. The aerobic bacteria positioned at very deep in biological layer will die because of the lack of oxygen. 6. Anaerobic organisms live in the inner biological layer.

TASK 3: GAP FILLING Complete the table below with appropriate words or phrases

microbes

aerobic

assimilating blended

flocculent

sludge

separation

biomass

insoluble

aeration tank

activated sludge

clumps

The activated sludge process is a wastewater treatment method in which the carbonaceous organic matter of wastewater provides an energy source for the production of new cells for a mixed population of microorganisms in an aquatic aerobic environment. The (1)……. convert carbon into cell tissue and oxidized end products that include carbon dioxide and water. In addition, a limited number of microorganisms may exist in (2)……. that obtains energy by oxidizing ammonia nitrogen to nitrate nitrogen in the process known as nitrification. The activated sludge process is an (3)……. biological treatment system. The essential units of the process are an (4)……., a secondary settling tank, a sludge return line from the secondary settling tank to the aeration tank and an excess (5)……. waste line. In an activated sludge process raw wastewater or more usually settled wastewater is aerated in an aeration tank for a period of 6 to 10 hours. During the aeration (for the upkeep of aerobic environment), the microorganisms in the wastewater multiply by (6)……. part of the influent organic matter. In this process, part of the organic matter is synthesized into new cells and part is oxidized to derive energy. The synthesis reaction, followed by subsequent (7)…….of the resulting biological mass and the oxidation reaction are

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the main mechanisms of BOD removal in the activated sludge process. The biomass is generally (8)……. and quick settling. It is separated from the aerated sewage in a secondary settling tank and a part of it is recycled to the aeration tank. Activated Sludge Process is an aerobic biological oxidation process in which wastewater is aerated in the presence of a flocculent mixed microbial culture known as Activated Sludge. Wastewater rich in organics (9)……. with return sludge rich in microorganisms is called ―Mixed Liquor‖. The microbes grow in number to remove both (10)……. and soluble organics from wastewater, stabilize them and they themselves flocculate to form into (11)……. which settle in the secondary sedimentation tank by gravity. The process derived its name from the fact that sludge containing active microorganisms is returned to increase the available (12)……. and to speed up the reaction.

Reading 3. Rotary Biological Contactor (RBC) RBC consists of a series of closely spaced circular discs of polystyrene or polyvinyl chloride. They are so spaced that wastewater and air can enter the space between the discs. The discs are partially submerged in wastewater and rotated slowly through it. RBC has its biofilm attached to plastic media that rotate into and out of trough of wastewater. The rotation causes turbulent mixing, circulation and aeration of the liquid contents in the trough. Biological growth gets attached to the surface of the discs and forms a slime layer over the surface of the discs to a thickness of 1 to 3 mm. The rotation alternately brings the biomass in contact with the organic matter of the wastewater and free atmosphere for the adsorption of oxygen. The disk rotation affects oxygen transfer and maintains the biomass in an aerobic condition. Thus complete aerobic conditions are maintained.

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Figure 21.1. Rotating biological contactor

TASK 4. COMPREHENSION QUESTIONS Answer the questions below

1. How can the slime layer be formed on the rotary contactor?

............................................................................................................................................................................................... 2. Why the disks are partially submerged in wastewater instead of fully submerged?

............................................................................................................................................................................................... 3. The outer of the slime layer over the surface is aerobic condition. How about the inner layer?

...............................................................................................................................................................................................

Reading 4. Anaerobic and Septic Tank

Anaerobic wastewater treatment is the biological treatment without the use of air or elemental oxygen. Many groups of anaerobic bacteria ―work‖ together in the absence of oxygen to degrade complex organic pollutants into methane and carbon dioxide (biogas). Their microbiology is more complex and delicate. In aerobiosis aerobes work individually to decompose organic matter. Anaerobiosis involves a number of chain reactions each being performed by a specific and specialized bacteria. Hydrolysis (conversion of solids into liquids), Acidogenesis (acid production) Acetogenic (acetate building) and Methanogenic (methane formation) phases are most common. Methane bacteria use acetic acid, hydrogen gas (H 2) and carbon dioxide (CO2) to generate methane (CH4)

Septic tanks

Septic tanks are used for the treatment of wastes from scattered, isolated and individual houses. It may be regarded as a downward flow sludge blanket system. The septic tank is an anaerobic treatment plant where (i) settling of solids (ii) floatation of grease (iii) anaerobic decomposition of organic matter and (iv) anaerobic digestion of sludge take place. A septic tank is a combined sedimentation and cum digestion tank. The removal of settleable solids and the anaerobic digestion of these solids are taking place simultaneously. The tank is kept completely covered at the top with a provision of a high vertical vent for the escape of the gases. Gases such as methane, carbon dioxide, and hydrogen sulphide are released during the digestion process. The effluent contains considerable BOD and at times may be more than that of the influent. The effluent contains considerable amount of dissolved and suspended putrescible organic solids

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and viable pathogens. The effluent must be treated before letting off into natural open drains or natural courses of water. It is disposed of either by sub-surface irrigation or into soak pits. Due to anaerobic digestion of sludge and consequent release of gases, appreciable reduction in the volume of sludge takes place. It is essential that adequate storage capacity be provided so that the deposited sludge remains in the tank for a sufficient length of time to undergo decomposition or digestion before being withdrawn. In general, sludge should be removed once in every 3 to 5 years.

TASK 5. COMPREHENSION QUESTIONS Answer the questions below

1. How many steps are there in anaerobic processes? ............................................................................................................................................................... 2. How can the anaerobic bacteria get oxygen? ............................................................................................................................................................... 3. Where the septic tank can be applied? ............................................................................................................................................................... 4. Which processed can occur in the septic tank? ............................................................................................................................................................... 5. Whether the septic tank is a opened or closed tank? Why? ............................................................................................................................................................... 6. Why volume of sludge is reduced dramatically in septic tank?

.................................................................................................................................................

TASK 6: GAP FILLING Complete the table below with appropriate words or phrases

bacteria

Biological processes

Chemical/physical method

suspended

floating

removes

sludge

stage

Secondary wastewater treatment: treatment (following primary waste water treatment) involving the (1)…….of reducing suspended colloidal and dissolved organic matter in effluent from primany treatment systems and which generally (2)……. 80 to 95 percent of the Biochemical Oxygen Demand (BOD) and suspended matter. Secondary wastewater treatment may be accomplished by biological or (3)……..

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Activated (4)……. And trickling filters are two of the most common means of secondary treatment. It is accomplished by bringing together waste, (5)……., and oxygen in trickling filters or in the activated sludge process. This treatment removes (6)……. and settleable solids and about 90 percent of the oxygendemanding substances and (7)……. solids. Disinfection is the final (8) ……. of secondary treatment.

TASK 7: GAP FILLING Complete the table below with appropriate words or phrases

aeration

basins

chlorine

conventional

inorganic

quality

screens

solid

Tertiary waste water treatment –selected biological, physical, and chemical separation processes to remove organic and (1)…….. substances that resist (2)……. Treatment practices; the additional treatment of effluent beyond that of primary and secondary treatment methods to obtain a very high (3)……. of effluent. The complete wastewater treatment process typically involves a three-phase process: (1) First, in the primary waste water treatment process, which incorporates physical aspects, untreated water is passed through a series of (4)……. to remove (5)……. Wasters; (2) Second, in the secondary waste water treatment process, typically involving biological and chemical processes, screened waste water is then passed a series of holding and (6)……. Tanks and ponds; and (3) Third, the tertiary wastewater treatment process consists of flocculation (7)……., clarifiers, filers, and (8)…….. basins or ozone or ultraviolet radiation processes.

TASK 8: How to find good keywords Find the keywords in reading paragraphs 4 and 5.

TASK 9: Summary In about 5 sentences, summarize the main idea in paragraphs 4 and 5.

TASK 10: Glossary

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Search your knowledge, look up your dictionary, internet or ask your instructor to clarify the definition and Vietnamese meaning of the following terminologies.

No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

Terminology

Definition

activated sludge aeration tank aerobe aerobic algae anaerobic anaerobic anoxic attached-growth process autotrophic autotrophic biofilm

biomass biotower ceramic clarifier

clumps cum digestion effluent facultative fixed-film process

flocculent fungi heterotrophic Hydrolysis impurity Methanogenic nutrient penetrate permeable media primary treatment saprophytes secondary treatment septic tank sewage

169

Vietnamese

36 37 38

slime substrate trickling filter

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Unit 22.

Browning Reaction

Objective: After reading this unit, you should able to Know what browning reaction is. Know the browning reaction keywords.

Browning reactions are some of the most important phenomena occurring in food during processing and storage. They represent an interesting research for the implications in food stability and technology as well as in nutrition and health. The major groups of reactions leading to browning are enzymatic phenol oxidation and so-called nonenzymatic browning.

Enzymatic browning can affect fruits, vegetables, and seafood in either positive or negative ways. It is catalyzed by the enzyme polyphenol oxidase. These reactions, for instance, may contribute to the overall acceptability of foods such as tea, coffee, cocoa, and dried fruits. Melanoidins, produced as a consequence of polyphenol oxidase (PPO) activity, may exhibit antibacterial, antifungal, anticancer, and antioxidant properties. Despite these positive effects, enzymatic browning is considered one of the most devastating reactions for many exotic fruits and vegetables, in particular tropical and subtropical varieties. Enzymatic browning is especially undesirable during processing of fruit slices and juices. Processing such as cutting, peeling, and bruising is enough to cause enzymatic browning. Since enzymatic browning can affect the color, flavor, and nutritional value of these foods, it can cause tremendous economic losses. Consequently, the methods addressed to inhibiting the undesired browning are focused on either inhibiting or preventing PPO activity in foods. Commonly, an effective control of enzymatic browning can be achieved by a combination of antibrowning agents. A typical combination might consist of a chemical reducing agent such as ascorbic acid, an acidulant such as citric acid, and a chelating agent like EDTA (ethylenediaminetetraacetic acid). In addition, transgenic fruits carrying an antisense PPO gene show a reduction in the amount and activity of PPO, and the browning potential of transgenic lines is reduced compared with the nontransgenic ones.

Nonenzymatic browning is the most complex reaction in food chemistry due to the large number of food components able to participate in the reaction through different pathways, giving rise to a complex mixture of products. It is referred to as the Maillard reaction when it takes place between free amino groups from amino acids, peptides, or proteins and the carbonyl group of a reducing sugar. The Maillard

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reaction is one of the main reactions causing deterioration of proteins during processing and storage of foods. This reaction can promote nutritional changes such as loss of nutritional quality or reduction of protein digestibility and amino acid availability. The rate of the Maillard reaction and the nature of the products formed depend on the chemical environment of food including the water activity (aw), pH, and chemical composition of the food system, temperature being the most important factor. Processes such as baking, frying, and roasting are based on the Maillard reaction for flavor, aroma, and color formation. Maillard browning may be desirable during manufacture of meat, coffee, tea, chocolate, nuts, potato chips, crackers, and beer and in toasting and baking bread. In other processes such as pasteurization, sterilization, drying, and storage, the Maillard reaction often causes detrimental nutritional (lysine damage) and organoleptic changes. Resultant products of the reaction of different amino acid and sugar model systems presented different properties: antimutagenic, antimicrobial and antioxidative. One of the most important objectives must be to limit nutritional damage of food during processing. In this sense, many studies have been performed find useful heat-induced markers derived from the Maillard reaction, and most of them have been proposed to control and check the heat treatments and/or storage of foods.

During nonenzymatic browning of foods, various degradation products are formed via caramelization of carbohydrates, without amine participation. Caramelization occurs when surfaces are heated strongly, during the processing of foods with high sugar content. Caramelization is desirable to obtain caramel-like flavor and/or development of brown color in certain types of foods. Caramel flavoring and coloring, produced from sugar with different catalysts, is one of the most widely used additives in the food industry. However, caramelization is not always a desirable reaction due to the possible formation of mutagenic compounds and the excessive changes in sensory attributes that could affect the quality of certain foods.

Glossary 1. Oxidation: the addition of oxygen to a compound with a loss of electrons 2. Antibacterial: Anything that destroys bacteria or suppresses their growth or their ability to reproduce

3. Antifungal: Destroying or inhibiting the growth of fungi. 4. Antioxidant: substances that may protect your cells against the effects of free radicals. 5. Sterilization: the elimination of microbiological organisms to achieve asepsis 6. Chelating agent: Chemicals are used in food manufacture to remove traces of metal ions which might otherwise cause foods to deteriorate and clinically to reduce absorption of a mineral, or to increase its excretion; e.g. citrates, tartrates, phosphates, and EDTA.

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7. Digestibility: the proportion of a feed or diet which can be digested by the normal animal of the subject species.

8. Roasting: a cooking method that uses dry heat and cause caramelization or Maillard browning of the surface of the food, which is considered a flavor enhancement

9. Detrimental: Causing damage or harm; injurious.

TASK 1. Based on the text you just read, choose the best answer to complete these statements

1. Browning reactions are a result of a. enzymatic phenol oxidation b. nonenzymatic browning c. Both a and b 2. The effects of browning reaction in food is a. positive and negative b. positive c. negative 3. Melanoidins is a product of a. Enzymatic activity b. Nonenzymatic activity c. Both a and b 4. The Maillard reaction is a reaction a.

Between an amino acid and reducing sugar

b. Between sugar and sugar c.

Only amino acids

5. Caramelization occurs between a.

Amino acids and sugar

b.

Sugar and sugar

c.

Both a and b

6. Products of browning reaction only inhibit a.

Oxidation and cancer

b.

Microorganism and oxidation

c.

Microorganism, cancer and oxidation

d.

a, b and c are wrong

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TASK 2. Whether the below sentence is true (T) or false (F)

1. Heat-induced markers derived from the Maillard reaction are not useful to control and check the heat treatments of food. 2. The enzyme polyphenol oxidase is a catalyst of nonenzymatic browning reaction 3. Browning colour is produced by enzymatic phenol oxidation and Maillard reaction. 4. Enzymatic browning is necessary during processing of fruit slices and juices 5. Browning reactions are only happened in food processing. 6. Melanoidins are produced by polyphenol oxidase (PPO) activity 7. EDTA can be used as a chelating agent in the prevention of PPO activity. 8. Antibrowning agents can not control enzymatic browning when they are combined to PPO activity. 9. Because of Maillard reaction, organoleptic changes usually happen during pasteurization, sterilization, drying, and storage. 10. The Maillard reaction happens between free amino groups from amino acids, peptides, or proteins and the carbonyl group of a reducing sugar. 11. The nonenzymatic reaction do not affect to baking, frying, and roasting 12. Denaturation of proteins during processing and storage of foods is a consequence of the Maillard reaction 13. Products of caramelization can be used as food additives

TASK 3. These sentences contain underlined words that you have seen in the texts. Each sentence is followed by two correct definition of the underlined word. Choose the one definition that is appropriate for the given sentence

1. Cutting is a food processing a. An outgrowth of tissue b. A series of operations performed in the making or treatment of a product

2. His implication of immediate changes surprised us. a. The act of implying b. Associations, connections

3. Many phenomena related to weather are not fully understood a. A fact or occurrence b. Something that is impressive or extraordinary.

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4. Changes in student enrollment that have catalyzed the educational system. a. Increase the rate of a chemical reaction by catalysis. b. Transform

5. You are devastating my car by pouring sugar in the tank a. Destroy completely b. Overwhelm or overpower

6. Exotic tropical plants are grown in a greenhouse a. From another part of the world or foreign b. Different or unusual

7. You can not eat orange if it is not peeled a. Remove the outer layer b. Take off one's clothes

8. Preservative, a substance that inhibits spoilage a. To decrease, limit, or block the action or function of an enzyme or organ b. To prevent or decrease the rate of a reaction

9. His health had deteriorated while he was in prison. a. To grow worse or degenerate b. To diminish or impair in quality, character, or value

TASK 4. Demonstrate your understanding of some of the details in the reading. Based on the text you just read, give short answers to the questions

1. What is difference between Maillard reaction and caramellization? 2. How many are types of browning reactions usually happened in food? 3. Are there two nonenzymatic reactions that produce browning color? 4. What kinds of food are affected by enzymatic browing?

5. How do food technologists inhibit the enzymatic browning? TASK 5: How to find good keywords Find the keywords in reading paragraph. TASK 6: Summary In about 5 sentences, summarize the main idea in paragraph.

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Unit 23.

Food Additives

Objective: After reading this unit, you should able to Know what food additive is. Know the food additives keywords.

A food additive is a substance (or a mixture of substances) which is added to food and is involved in its production, processing, packaging and/or storage without being a major ingredient. Additives or their degradation products generally remain in food, but in some cases they may be removed during processing. Additives such as vitamins, minerals, amino acids and amino acid derivatives are utilized to increase the nutritive value of food. A particular diet may also require the use of thickening agents, emulsifiers, sweeteners, etc. Color, odor, taste and consistency or texture, which is important for the sensory value of food, may decrease during processing and storage. Such decreases can be corrected or readjusted by additives such as pigments, aroma compounds or flavor enhancers. Development of ―off-flavor‖, for instance, derived from fat or oil oxidation, can be suppressed by antioxidants. Food texture can be stabilized by adding minerals or polysaccharides, and by many other means. The current forms of food production and distribution have increased the demand for longer shelf life. Furthermore, the world food supply situation requires preservation by avoiding deterioration as much as possible. The extension of shelf life involves protection against microbial spoilage, for example, by using antimicrobial additives and by using active agents which suppress and retard undesired chemical and physical changes in food. The latter is achieved by stabilization of pH using buffering additives or stabilization of texture with thickening or gelling agents, which are polysaccharides.

Glossary 1. Degradation: Decomposition of a compound by stages 2. Minerals: solid chemical substance is formed through geological processes 3. Derivatives: a compound obtained from, or regarded as derived from, another compound 4. Emulsifiers: a type of surfactant typically used to keep emulsion (mixtures of immiscible fluids) well

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5. Disperse: cause to separate 6. Suppressed ≈ inhibit or prevent 7. Texture: the properties held and sensations caused by the external surface of objects received through the sense of touch TASK 1 Check your understanding of the texts you just read. Based on the reading, are the following statements true (T), false (F) or not given (NG)

1. Microbial spoilage is one of the most important factor which reduce the shelf life of food 2. Additives (vitamins, minerals, amino acids and amino acid derivatives) are utilized to enhance the nutritive value of food 3. The sensory value of food can be decreased because of processing and storage 4. The nutritive value of food is decreased by using vitamins, minerals and amino acids 5. The flavor of processed food is not lost by oil oxidation 6. The sensory value of food is evaluated by color, odor and taste 7. A food additive is a substance or a mixture of substances which added to food as food ingredient.

TASK 2. Demonstrate your understanding of some of the details in the reading. Based on the text you just read, give short answers to the questions.

1. How is oil oxidation reduced?

2. What is a food additive? 3. Why is preservation required in foodstuff? 4. What are food additives used to enhance the nutrients value of food? 5. How is food texture stabilized? 6. TASK 3. Choose one of the words to fill in the blank in each sentence.

substance odor

antioxidants

preservation

processing

flavor

shelf life storage

1. The extension of ____________ involves protection against microbial spoilage.

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2. Color, __________ , taste and consistency or texture, which is important for the sensory value of food, may decrease during processing and storage. 3. A food additive is _____________ which is added to food and is involved in its production, processing, packaging and/or storage without being a major ingredient 4. The world food supply situation requires ____________ by avoiding deterioration as much as possible. 5. Development of ―off-flavor‖, for instance, derived from fat or oil oxidation, can be suppressed by ____________

TASK 4: How to find good keywords Find the keywords in reading paragraph. TASK 5: Summary In about 5 sentences, summarize the main idea in paragraph.

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Unit 24.

Beer Production

Objective: After reading this unit, you should able to Know how beer can be produced. Know the beer production keywords.

The word beer comes from the Latin word Bibere (to drink). The basic ingredients for most beers are malted barley, water, hops and yeast. Compared to most other alcoholic beverages, beer is relatively low in alcohol. The highest average strength of beer (alcohol by volume (ABV) indicates the millilitres of ethanol per 100ml of beer) in any country worldwide is 5.1% and the lowest is 3.9%. Beer production is divided into four distinct processes such as malting, mashing, wort boiling and fermentation

1) Malting (germination of the barley or other cereal and drying of the germinated cereal): Malting can be divided into three stages, steeping, germination and kilning. The purpose of malting is to provide the correct environment for the grain to synthesize hydrolytic enzymes. For successful malting there are three basic requirements, namely grain viability, water and oxygen.

2) Mashing (the extraction of the ground malted barley with water): The process of mashing involves dissolving the substances in malt that are immediately soluble in warm water containing specified salts and a specific pH and rendering the substances which are insoluble in their natural state soluble through enzymatic. The most important reaction in mashing is the conversion of starch to smaller dextrin and maltose by the action of barley α- amylase and ß-amylase, which produces wort that is approximately 70-80% fermentable carbohydrates. This system permits the use of corn grits and rice as adjuncts, and the beer thus produced is lighter in taste. The final wort will vary depending on: the enzyme complement contributed to the mash by the malt; the mashing temperature; and the duration of the mashing. The separation of the wort from the mash solids is usually by lauter tun (or tub) or by mash filter. Lautering is the name given to the process of separating the liquid part of the mash (the wort) from the undissolved part (the spent grains).

3) Wort boiling: After mashing is complete, the filtered sweet wort is transferred to the kettle (or copper) and boiled for up to 2 hours. The objectives achieved by wort boiling are stabilization,

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concentration, sterilization, flavor development and hop extraction. After boiling, the spent hops, precipitated proteins and other insoluble material, referred to as ‗trub‘, are separated from the wort which is cooled. The purpose of the ‗hot and cold breaks‘ is to reduce the material present that could later precipitate in the finished beer as a haze. During wort cooling, aeration/oxygenation of the wort is carried out to permit the yeast to ferment efficiently.

4) Fermentation: Fundamentally, brewing yeast can be divided into ale and lager strains, the former type collecting at the surface of the fermenting wort and the latter settling at the bottom of a fermentation. Both types need a little oxygen to trigger off their metabolism, but otherwise the alcoholic fermentation is anaerobic. Fermentation is completed when the desired alcohol content has been reached and when an unpleasant butterscotch flavour, which develops during all fermentations, has been mopped up by yeast. Nowadays, the majority of beers receive a relatively short conditioning period after fermentation and before filtration. This conditioning is ideally performed at−1◦C or lower (but not so low as to freeze the beer) for a minimum of 3 days, under which conditions more proteins drop out of the solution, making the beer less likely to cloud in the package or glass. Finally, the filtered beer is adjusted to the required carbonation before packaging into cans, kegs, or glass or plastic bottles.

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Glossary Butterscotch: a flavoring made from melting butter and brown sugar together. Mopped: remove with Anaerobic: "without oxygen" Sterilization: a technique for destroying microorganisms or inanimate objects using heat, water, chemicals, or gases Concentration: increase in density Stabilization: the act of stabilizing something or making it more stable Conversion: a change or adaptation in form, character, or function Insoluble: that cannot be dissolved Kilning: any of various ovens for hardening, burning, or drying substances such as grain, meal, or clay, especially a brick-lined oven used to bake or fire ceramics. Germination: The beginning or the process of development of a spore or seed Steep: To make thoroughly wet Yeast: Any of various similar fungi

TASK 1. Check your understanding of the texts you just read. Based on the reading, are the following statements true (T), false (F) or not given (NG)

1. _____ The average strength of beer in any country worldwide is from 3.89% to 5.5%. 2. _____ The alcohol content of beer is higher than alcoholic beverages. 3. ______ Hydrolytic enzymes are synthesized by malting process. 4. _____ The alcohol content of beer is defined as the millilitres of ethanol per 1000ml of beer 5. _____ There are four major ingredients to producing beers. 6. _____ Barley starch supplies most of the sugars from which the alcohol is derived in the majority of the world‘s beers. 7. _____ There are three basic requirements such as grain viability, water and oxygen in malting process.

8. _____ Malting can be divided into three stages such as soaking, germination and kilning. 9. _____ The most important reaction in mashing is the conversion of starch to smaller dextrin and maltose which produces wort

10. _____ Wort consists of about 70-80% fermentable carbohydrates. 11. _____ The lauter tun and mash filter are used to separate the wort from the mash solids 181

12. _____ Trub is separated from the wort which is cooled. 13. _____ The alcoholic fermentation is not aerobic. 14. _____ There are two kinds of brewing yeast that are ale and lager strains 15. _____ The purpose of wort boiling are concentration, sterilization, flavor development and hop extraction.

16. _____ The beer is less cloud in the package or glass when it is only stored at −1◦C for a minimum of 3 days.

17. ______ The hops have two principal components: resins and essential oil

TASK 2Demonstrate your understanding of some of the details in the reading. Based on the text you just read, give short answers to the questions.

1. What kinds of enzymes are used in the mashing process? How is it worked? 2. What are the basic ingredients of beer? 3. How long is the filtered wort boiled after mashing process? 4. How many processes are defined in beer production? 5. What is ―trub‖? 6. Why is the wort boiled? 7. Is the filtered beer adjusted to the required carbonation before packaging? 8. What is the purpose of malting in beer production? 9. When is fermentation completed? 10.What container is used to separate the wort from the mash solids? TASK 3. Choose one of the words to fill in the blank in each sentence. You may have to change the form of the word to fit the sentence

filter haze

keg

fermentation

filtration

aeration

kettle

fermentable

cloud liquid

ale

mop undissolve

1. The __________ beer is adjusted to the required carbonation before packaging into cans, __________ , or glass or plastic bottles. 2. The majority of beers receive a relatively short conditioning period after _____________ and before ___________

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3. The successful condition is at−1◦C or lower (but not so low as to freeze the beer) for a minimum of 3 days, making the beer less likely to ________ in the package or glass. 4. Brewing yeast can be divided into __________ and lager strains. 5. __________ is completed when the desired alcohol content has been reached and when an unpleasant butterscotch flavour, which develops during all fermentations, has been ________ up by yeast. 6. The purpose of the ‗hot and cold breaks‘ is to reduce the material present that could later precipitate in the finished beer as a __________. 7. During wort cooling, __________ of the wort is carried out to permit the yeast to ferment efficiently. 8. The filtered sweet wort is transferred to the _______ and boiled for up to 2 hours. 9. The most important reaction in mashing is the conversion of starch to smaller dextrin and maltose by the action of barley α- amylase and ß-amylase, which produces wort that is approximately 7080% ____________ carbohydrates 10. Lautering is the name given to the process of separating the ________ part of the mash (the wort) from the __________ part (the spent grains).

TASK 4.Show your understanding of the reading. Based on the text you just read, choose the best answer to complete these statements

1. Beers are stored at−1◦C or lower for a minimum of 3 days:

a. After fermentation b. Before filtration. c. During filtration d. a and b 2. The carbonation is suggested to control the filtered beer a. Before packaging b. After packaging c. During packaging 3. Fermentation is completed when a. The desired alcohol content has been reached b. An unpleasant butterscotch flavour has been mopped up by yeast. c. The substances in malt are dissolved to the warm water. d. a and b e. a, b and c

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4. The wort is cooled lead to separate

a. The spent hops b. Precipitated proteins and other insoluble material c. Trub 5. The stages of malting can be defined as

a. Steeping and germination b. Germination and kilning c. Steeping, germination and kilning TASK 5.Check your understanding of details. Complete the sentences on the left by choosing the best phrase on the right.

1. Ingredients

1. A component of a mixture or compound

2. Yeast

2. Any of various single-celled fungi that reproduce asexually by budding or division

3. Steeping 4. Germination

3. Let sit in a liquid to extract a flavor or to cleanse

5. Kilning

4. The process whereby seeds or spores sprout and begin to grow

6. Hydrolytic

5. Firing or burning or drying

7. Insoluble

6. The removal or separation of water

8. Conversion

7. Incapable of being dissolved

9. Concentration

8. The act of changing from one use or function or purpose to another

10. Sterilization 11. Anaerobic

9. Increase in density 10. The act of making an organism unable to reproduce 11. Living or active in the absence of free oxygen

TASK 6: How to find good keywords Find the keywords in reading paragraph. TASK 7: Summary In about 5 sentences, summarize the main idea in paragraph.

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Unit 25.

Modified Atmosphere Packaging

Objective: After reading this unit, you should able to Know what modified atmosphere packaging is. Know the modified atmosphere packaging keywords.

Modified Atmosphere Packaging MAP (or gas flushing) is the introduction of an atmosphere, other than air, into a food package without further modification or control. MAP is used to extend a product shelf life to give processors additional time to sell the food without sacrificing quality or freshness. Successful MAP requires raw materials with a low microbiological count and strict temperature control throughout the process. The three main gases used in MAP are nitrogen, oxygen and CO 2. Nitrogen is inert and tasteless, with low solubility in both water and fats. It is used to replace oxygen and thus inhibit oxidation or the growth of aerobic microorganisms. Oxygen is used in MAP to maintain the red colour of unprocessed meats. For fresh produce, the aim of MAP is to minimize respiration and senescence without causing damage to metabolic activity that would result in loss of quality. Typically, the shelf life of fresh red meat is extended from 3 days to 7 days at 0–2ºC by packaging in an 80% O2 / 20% CO2 atmosphere, but this may cause problems of oxidative rancidity in fatty fish or development of off-colours in cured meats. Pork, poultry and cooked meats have no oxygen requirement to maintain the colour, and a higher carbon dioxide concentration (90%) is possible to extend the shelf life to 11 days. In fresh fruits and vegetables, a concentration of 10–15% carbon dioxide is required to control decay. For processed (that is non-respiring) foods, atmospheres should be as low as possible in oxygen and as high as possible in CO 2 without causing the pack to collapse or produce changes to the flavor or appearance of the product. A high carbon dioxide concentration prevents mould growth in cakes and increases the shelf life to 3–6 months. Other bakery products have the shelf life increased from 2 days to 3–4 weeks. In MAP, the absorption of CO2 should be carefully controlled to prevent too great a reduction in gas pressure which causes collapse of the pack. Nitrogen is often added as a filler gas to prevent pack collapse. The relative volume of gas and product is important to ensure the effectiveness of MAP. There should therefore be adequate space between the product and the package to contain the correct amount of gas.

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Glossary

Sacrifice (v): the act of losing or surrendering something Inert (adj): Not readily reactive with other elements Tasteless (adj): Lacking flavor

TASK 1. Show your understanding of the reading. Based on the text you just read, choose the best answer to complete these statements.

1. The property of nitrogen is a. Inert and tasteless b. Soluble in both water and fats c. Inert and tastiness d. a and b e. b and c 2. MAP is successful when a. Raw materials contain low amount of microorganism b. Temperature is controlled strictly. c. a and b 3. A high concentration of carbon dioxide prevents mould growth in cakes and increases the shelf life to a. 3–6 months b. More than 6 months c. Less than 3 months 4. MAP is used to a. Extend a product shelf life b. Kill the pathogenic bacteria c. a and b 5. Nitrogen in MAP is used to a. Replace oxygen b. Replace hydrogen c. Replace CO2 6. To prevent pack collapse by

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a. Nitrogen b. Hydrogen c. Oxygen d. a, b and c 7. The red colour of raw meats is maintained in MAP by a. Oxygen b. Hydrogen c. Nitrogen d. CO2 8. The main gases used in MAP are a. Hydrogen, oxygen and CO2 b. Nitrogen, oxygen and CO2 c. Oxygen and CO2 9. The effectiveness of MAP is depended on a. Volume of gas b. Product c. a and b TASK 2. Check your understanding of the texts you just read. Based on the reading, are the following statements true (T) or false (F) 1. Nitrogen, hydrogen and CO2 are used in MAP 2. Low microbiological count and strict temperature control throughout the MAP process are the requirements of raw materials 3. Oxygen is not used in MAP to maintain the red color of unprocessed meats 4. A filler gas to prevent pack collapse is defined as nitrogen. 5. Nitrogen is high soluble in both water and lipids.

TASK 3. Demonstrate your understanding of some of the details in the reading. Based on the text you just read, give short answers to the questions.

1. How is the shelf life of fresh red meat extended from 3 days to 7 days at 0–2ºC? 2. Is the shelf life of fresh red meat extended for 3 days at 0–2ºC by packaging in an 80% CO2 / 20% O2 atmosphere? 3. Why is nitrogen added to the pack?

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4. What is the purpose of MAP in food processing? TASK 4: How to find good keywords Find the keywords in reading paragraph. TASK 5: Summary In about 5 sentences, summarize the main idea in paragraph.

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Unit 26.

Emulsification and Homogenization

Objective: After reading this unit, you should able to Know what emulsification and homogenization are. Know the emulsification and homogenization keywords.

Emulsification is the formation of a stable emulsion by the intimate mixing of two or more immiscible liquids, so that one (the dispersed phase) is formed into very small droplets within the second (the continuous phase). Naturally occurring proteins and phospholipids act as emulsifying agents, but in food processing synthetic agents (including esters of glycerol or sorbitan esters of fatty acids) are more effective and these are normally used. Examples of emulsified products include margarine and low-fat spreads, salad cream and mayonnaise, sausagemeat, ice cream and cakes. In solid food emulsions the texture is determined by the composition of the food, the homogenisation conditions and post-processing operations such as heating or freezing. In all food emulsions, degradative changes such as hydrolysis or oxidation of pigments, aroma compounds and vitamins, and microbial growth on the finely dispersed material, are minimised by careful control over the processing, packaging and storage conditions. Flavour and aroma are improved in many emulsified foods because volatile components are dispersed throughout the food and hence have greater contact with taste buds when eaten.

Homogenisation is the reduction in size (to 0.5–30 µm), and hence the increase in number, of solid or liquid particles in the dispersed phase by the application of intense shearing forces. Homogenisation is therefore a more severe operation than emulsification. Both operations are used to change the functional properties or eating quality of foods and have little or no effect on nutritional value or shelf life. In milk, homogenisation reduces the average size of fat globules from 4 µm to less than 1 µm, thereby giving the milk a creamier texture. Homogenisation has an effect on the colour of some foods (for example milk) because the larger number of globules causes greater reflectance and scattering of light.

Glossary

Immiscible (adj): incapable of being mixed to form a homogeneous substance

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Disperse (v): to scatter; distribute over a wide area

TASK 1. Check your understanding of the texts you just read. Based on the reading, are the following statements true (T) or false (F)

1. The colour of some foods is affected by homogenisation 2. Emulsification is that the continuous phase is formed into very small droplets within the dispersed phase 3. The homogenisation conditions is one of the major factor which affect to the texture of solid food emulsions 4. Emulsifying agents from natural is less effective than synthetic agents in food processing 5. Both homogenisation and emulsification have little or no effect on nutritional value or shelf life of food. 6. To control over the processing, packaging and storage conditions lead to reduce degradative changes in all food emulsions 7. Because volatile components are not dispersed throughout the food, flavour and aroma are not improved in many emulsified foods

TASK 2. Demonstrate your understanding of some of the details in the reading. Based on the text you just read, give short answers to the questions.

1. List the name of emulsifying agents from natural? 2. How does the milk get a creamier texture? 3. Why are flavour and aroma improved in many emulsified foods? 4. Why does homogenisation affect to the colour of some foods? 3. What kinds of food are produced as emulsified products? TASK 3. Choose one of the words to fill in the blank in each sentence. You may have to change the form of the word to fit the sentence. dispersed reduction

continuous

emulsification

salad cream

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sausagemeat

homogenisation margarine

1. Emulsification is the formation of a stable emulsion so that the __________ phase is formed into very small droplets within the ____________ phase 2. __________ is more severe operation than ____________ 3. ______________ has an effect on the colour of some foods 4. Homogenisation is the ________ in size and the application of intense shearing forces 5. Emulsified products consist of ___________ and low-fat spreads, mayonnaise and ____________, ____________ , ice cream and cakes.

TASK 4: How to find good keywords Find the keywords in reading paragraph. TASK 5: Summary In about 5 sentences, summarize the main idea in paragraph.

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Unit 27.

Biotechnology and Probiotic

Objective: After reading this unit, you should able to Know what biotechnology and probiotic are. Know the biotechnology and probiotic keywords.

Biotechnology has had a tremendous impact on the food industry. It has provided high-quality foods that are tasty, nutritious, convenient, and safe, and it has the potential for the production of even more nutritious, palatable, and stable food. The roots of biotechnology can be found in the ancient processes of food and beverage fermentation. These traditional technologies are present in almost every culture in the world and have evolved over many years without losing their traditional essence. Examples of these processes include the production of some well-known foods, such as bread, wine, yogurt, and cheese. These products, like many others (such as ripened sausages [salami], pickles, sauerkraut, soy sauce, vinegar, beer, and cider), are produced using the natural processes of living organisms (e.g., fermentation) — in other words, by using biotechnology. Some relatively new developments in these traditional products include bio-yogurts, or biogurts, which contain extra bacteria (usually probiotic organisms) that are not found naturally in the original food. Probiotics are live microbial food supplements that are available incorporated into many food products, primarily fermented dairy foods. The positive health effects attributed to lactic acid bacteria and foods fermented with these bacteria have been

long

recognized. Bacteria that produce lactic acid and are perceived to exert beneficial properties such as improved lactose digestion and resistance to pathogens are the common probiotics. Probiotic foods can be made in two ways: fermentation of raw ingredients by probiotics, with or without starter cultures, and addition of suitable concentrations of probiotics to the finished product. Probiotic fermentation of raw ingredients allows the bacteria to multiply and impart distinctive flavors and organoleptic changes to the food. The probiotic strains selected for each different food system will affect the qualities of the final product, depending on the type and amount of acids and other metabolites that are produced.

Glossary Palatable (adj): pleasant to taste

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Exert (v): to use forcefully or effectively Starter cultures: a culture containing yeast or bacteria that are used to start the process of fermentation or souring in making butter or cheese or dough Organoleptic (adj): Relating to perception by a sensory organ

TASK 1. Demonstrate your understanding of some of the details in the reading. Based on the text you just read, give short answers to the questions

1. Can the roots of biotechnology be found in the ancient processes of food and beverage fermentation? 2. Why does lactic acid bacteria and foods fermented with these bacteria attributed to the human health? 3. What kind of food products are used for probiotic? 4. How many ways can probiotic foods be made? 5. What does biotechnology contribute to food industry? 6. How is probiotic fermentation worked? 7. How are high-quality foods in biotechnology application? 8. What are the probiotics?

TASK 2. Check your understanding of the texts you just read. Based on the reading, are the following statements true (T) or false (F)

1. High-quality foods are usually provided by biotechnology 2. Qualities of the final products is affected by the probiotic strains in different food system 3. Biotechnology has the potential for the production of even more nutritious, palatable, and fast food.

4. Bioyogurts is products which contain probiotic that are found naturally in the original food. 5. The roots of biotechnology can be found in the ancient processes of food and beverage fermentation.

6. Probiotics are live microorganisms which added to food, primarily fermented dairy foods. 7. Distinctive flavors and organoleptic changes can be produced by probiotic fermentation of raw ingredients.

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8. Lactic acid bacteria are two beneficial properties in health effects such as improved lactose digestion and resistance to pathogens

9. The pathogen can not be resisted by probiotics 10. Probiotic can be only used in fermentation of raw ingredients

TASK 3. Show your understanding of the reading. Based on the text you just read, choose the best answer to complete these statements

1. Traditional products are produced by using a. the natural processes of living organisms b. biotechnology c. a and b d. tissue culture technique 2. Biotechnology has had a tremendous effect on a. Food industry b. Plant science c. Enviroment 3. Probiotic are a.

Live microorganisms that are added to food.

b. Non-digestible food ingredients c.

Fermented dairy foods

4. Biotechnology has provided high-quality foods that are a. Tasty and safe b. Nutritious c. Convenient d. a, b and c 5. Probiotics can be used in a.

Food fermentation

b.

Food supplement

c.

Food nutrition

d.

a and b

6. Fermented foods from lactic acid bacteria can contribute to health effects because that bacteria can

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a.

make digestion of lactose better

b.

Resist to pathogens

c.

a and b

7. Raw ingredients can be fermented by a.

Probiotics and starter cultures

b.

Only probiotics

c.

Only and starter cultures

d.

a and b

TASK 4. Choose one of the words to fill in the blank in each sentence. You may have to change the form of the word to fit the sentence.

tasty

safe

bio-yogurts

ancient probiotics

multiply lactic acid

fermentation qualities

1. Foods are produced by biotechnology that are ___________ , nutritious, convenient, and _____________ 2. the __________ processes of food and beverage ___________ are related to biotechnology. 3. __________ are developed traditional products by using probiotic organisms 4. ___________ are live microbial food supplements that are available incorporated into many food products, primarily fermented dairy foods. 5. ___________ bacteria are perceived to exert beneficial properties such as improved lactose digestion and resistance to pathogens 6. Bacteria can __________ because of probiotic fermentation of raw ingredients

7. The _________ of the final product is affected by the probiotic strains selected for each different food system. TASK 5: How to find good keywords Find the keywords in reading paragraph. TASK 6: Summary In about 5 sentences, summarize the main idea in paragraph.

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Unit 28.

Recent Advances in Food Biotechnology Research

Objective: After reading this unit, you should able to Know what recent advances in food biotechnology research are. Know the advances in food biotechnology research keywords.

Modern biotechnology involves molecular techniques that use whole or parts of living organisms to produce or improve commercial products and processes. It is a relatively new and rapidly evolving branch of molecular biology, which started with the creation of the first recombinant gene 30 years ago. They also have enhanced other aspects of our lives through the development of new detection methods for early diagnosis of many diseases such as arteriosclerosis, cancer, diabetes, Parkinson‘s, and Alzheimer‘s. Recent developments in biotechnology will allow the production of more nutritious, safer, tastier, and healthier food. Advances in genetic engineering are revolutionizing the way we produce and consume food, and it is quite possible that in the next decade a large percentage of the food we eat will be bioengineered.

Genetic engineering methods have been extensively used to increase the quantity of different nutrients (vitamins, essential amino acids, minerals, and phytochemicals) and enhance their availability in plants. There are two main methods for transferring genes into plants for production of transgenic plants: Agrobacterium-mediated transformation and microprojectile bombardment. With the development of transgenic technology, improvements in commercially important livestock species have become possible by transferring genes from related or unrelated species. Genetic improvement through biotechnology can be achieved in one generation, instead of the several generations required for traditional animal breeding methods. Although several methods of gene transfer have been developed, four methods are used today in the production of most transgenic animals: nuclear transfer, microinjection, viral vector infection, and embryonic stem cell transfer. On the other hand, the process of fermentation was effected by the action of microorganisms and that each microorganism responsible for a specific food fermentation could be isolated and identified. Now, with advanced bioengineering techniques, it is possible to characterize with high precision important food strains, isolate and improve genes involved in the process of fermentation,

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and transfer desirable traits between strains or even between different organisms. Biotechnology plays an important role in maintaining the safety of the food supply. The development of reliable methods to ensure the traceability of genetic material in the food chain is of great value to food manufacturers and consumers. Consumer confidence in food biotechnology will increase if better traceability methods are in place. Modern biotechnology tools are also applied to develop sensitive, reliable, fast, and cheap methods for detection of harmful pathogenic organisms such as E. coli O157:H7 and the infectious agent for mad cow disease. The applications of genetic engineering in the food industry are not limited to the manipulation of plant genomes. Animals and microorganisms also have been extensively researched to produce better food products. Further biotechnology advances will enhance the value and scope of the use of microorganisms in the food and pharmaceutical industry.

Glossary Molecular biology: the study of biology at a molecular level. The field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry Recombinant (adj): produced by the combining of genetic material from more than one origin Microinjection: the process of using a glass micropipette to insert substances at a microscopic or borderline macroscopic level into a single living cell Embryonic stem cell: stem cells derived from the undifferentiated inner mass cells of a human embryo. Stem cell: primal cells found in all multi-cellular organisms TASK 1. Show your understanding of the reading. Based on the text you just read, choose the best answer to complete these statements

1. Whole or parts of _______________ is used to produce or improve commercial products and processes in modern biotechnology a. living organisms b. microorganisms c. molecular techniques 2. Developments of food biotechnology produce ____________ recently

a. Nutritious and healthier food b. Safer and tastier food c. Nutritious, safer, tastier, and healthier food. 3. Genes can be transferred to plants by

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a. Agro-bacterium b. Gene gun c. a and b 4. The methods are used today in the production of most transgenic animals: a. Nuclear transfer and viral vector infection b. Microinjection c. Embryonic stem cell transfer. d. a, b and c 5. Food safety can be maintained by a. Biotechnology b. Microorganism c. Detection method TASK 2. Check your understanding of the texts you just read. Based on the reading, are the following statements true (T) or false (F) 1. Except for the safety of the food supply, biotechnology plays an important role in food development 2. The quantity of nutrients is increased by molecular engineering methods in plants 3. The inhibition of the applications of genetic engineering in the food industry is manipulation of plant genomes 4. Detection of harmful pathogenic organism can be expensive by modern biotechnology tools 5. There are four methods in the production of most transgenic animals 6. The action of microorganisms can affect to the process of fermentation TASK 3. Demonstrate your understanding of some of the details in the reading. Based on the text you just read, give short answers to the questions

1. How many methods used for transferring genes into plants ? 2. Can genetic improvement through biotechnolog be achieved in one generation? 3. What are methods are used in the production of most transgenic animals? 4. What are biotechnology advances in the future? 5. Why are modern biotechnology tools applied to develop sensitive, reliable, fast, and cheap methods? TASK 5: How to find good keywords

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Find the keywords in reading paragraph. TASK 6: Summary In about 5 sentences, summarize the main idea in paragraph.

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Unit 29.

Food Processing

Objective: After reading this unit, you should able to Know several food processing process. Know the food processing process keywords.

Reading 1. How are biscuits made? Biscuits are a traditional type of flour confectionery which were, and can still be made and baked in a domestic kitchen. Now they are made mostly in factories on large production plants. These plants are large and complex and involve considerable mechanical sophistication. Forming, baking and packaging are largely continuous operations but metering ingredients and dough mixing are typically done in batches. There is a high degree of mechanization in the biscuit industry but at present there are very few completely automatic production plants. This means that there is a high degree of dependence on the operators are skilled in the tasks they have to do and this involves responsibility for product quality. As part of their training they must know about the ingredients and their roles in making biscuits. They must be aware of the potential ingredient quality variations and the significance of these. There are basically two types of biscuit dough, hard and soft. The difference is determined by the amount of water required to make a dough which has satisfactory handling quality for making dough pieces for baking. Hard dough has high water and relatively low fat (and sugar) contents. The dough is tough and extensible (it can be pulled out without immediately breaking), like tight break dough. The biscuits are either crackers or in a group known as semi-sweet or hard sweet. Soft doughs contain much less water and relatively high levels of fat and sugar. The dough is short, (breaks when it is pulled out) which means that is exhibits very low extensible character. It may be so soft that it is pourable. The biscuits are of the soft eating types which are often referred to as ―cookies‖. There are a great number of biscuit types made from soft doughs and a wide variety of ingredients may be used.

TASK 1: COMPREHENSION QUESTIONS Answer the questions below

1. Which primary material are biscuits made from? ....................................................................................................................................................................

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2. How to distinguish hard doughs and soft doughs? .................................................................................................................................................................... 3. What‘s difference between crackers and cookies? ....................................................................................................................................................................

TASK 2: TRUE OR FALSE Decide whether the following statements are true (T) or false (F). 1. There‘re two primary processes making biscuit 2. It is possible that biscuits are made from rice flour 3. More thermal, baking is more effective 4. Crackers are made from materials difference cookies

TASK 3: GAP FILLING Complete the table below with appropriate words or phrases

Biscuits

structure

baked

bake

machinery

The machinery used to make biscuits is designed to suit the type of dough needed and to develop the (1)………….. and shape of the individual biscuits. Secondary processing, which is done after the biscuit has been (2)…………, and packaging biscuits are specific to the product concerned. There is normally a limited range of (3)………..types that can be made by a given set of plant (4)…………….. Many biscuit production plants (5)…………at the rate of 1000 – 2000 kg per hour and higher rates are not unusual. Given this and the sophistication of the production line it is most economical to make only one biscuit type for a whole day or at least an eight hour shift. Start-ups and changeovers are relatively inefficient.

TASK 4: MATCHING Match a word or phrase in A with its definition in B Doughs

A soft, thick mixture of dry ingredients, such as flour or meal, and liquid, such as water, that is kneaded, shaped, and baked, especially as bread or pastry

Flour

A soft, fine powder

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Ingredient

a component of a mixture, compound, etc., esp in cooking

Bake

To harden or dry (something) by subjecting to heat in

Structure

The way in which parts are arranged or put together to form a whole; makeup

shape

A form or condition in which something may exist or appear

TASK 5: How to find good keywords Find the keywords in reading paragraph. TASK 6: Summary In about 5 sentences, summarize the main idea in paragraph.

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Reading 2. Quality criteria for fresh produce: appearance, texture, flavor and aroma The specific qualities required in fruits and vegetables will depend on their end-use and the selection of appropriate cultivars for particular products is of paramount importance. The quality of an individual product is also affected by its specific pre-harvest ―experience‖. So, for example, the position of a fruit on the tree will determine its nutrient and water status and its exposure to environmental factors such as sunlight or pests and diseases. All these factors may ultimately influence post-harvest shelf-life. Experience may enable those who regularly handle certain produce types to predict variations in shelf-life of produce form different sources, for example, based on soil type or weather factors before and during harvest.

Fresh fruits and vegetables are not considered to be high-risk products with respect to food safety as the normally become completely undesirable for consumption long before any hazardous microorganisms or toxins might develop. There is, however, evidence that sealing fresh vegetables in modified atmosphere packaging may extend shelf-life, while still allowing the growth of pathogenic bacteria, in particular Listeria spp and Escherichia coli O157. For most fresh produce, shelf-life is best defined as the period within which the product retains acceptable quality for sale to the processor or consumer. It is necessary, therefore, to identify what ―acceptable quality‖ means before it can be decided at what point the product no longer satisfies those expectations.

For the fresh produce market, specific minimum quality standards exist in many countries, however, owing to the international nature of the fresh produce market, there is a trend towards international standardization of quality grades. The European Commission was one of the first organizations to develop international standards for fresh fruits and vegetables. Many of these standards have been adopted by the Organization for Economic Cooperation and Development (OECD). Usually, standards required for multiple retail outlets are considerably more stringent than these minimum standards and will be defined for the supplier by the retailer. Providing the quality standards have been met, the factors which limit storage and shelf-life fall into the following categories: appearance, texture and flavor/aroma.

TASK 7: COMPREHENSION QUESTIONS Answer the questions below

1. Which factors influence post-harvest shelf-life? .................................................................................................................................................................... 2. Why are fresh fruits and vegetables considered to be high-risk products?

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.................................................................................................................................................................... 3. How to provide the quality standards with fresh fruits? ....................................................................................................................................................................

TASK 8: TRUE OR FALSE Decide whether the following statements are true (T) or false (F).

1. There are 5 factors affected quality of pre-harvest product 2. Identify ―acceptable quality‖ means is necessary 3. OECD is a organization which sets international standards for fresh fruits and vegetables

TASK 9: GAP FILLING Complete the table below with appropriate words or phrases

Vital

appearance

fibers

color

tissues

aromatic

aroma

Appearance

It is the key factor for consumer in making purchases of fresh produce. Displays of fruits and vegetables are characterized by uniformity of size, shape and color. ……….. components of visual quality include color and color uniformity, glossiness, and absence of defects in shape or skin finish and freedom from disease. The importance of appearance in the processing industry will depend on which part of the produce is used in the product and whether the ……….can readily be enhanced during processing. Internal fresh …………. is usually more important than peel color. Size and shape may be highly important where processing is automated rather than manual, however, for some products these attributes are less important.

Texture

Eating quality includes a complex of textural properties which are not readily defined or measured. Crisp firm ………. are generally desired in vegetable crops; however, the development of tough ………… during storage in stem crops such as asparagus is not at all acceptable. Although some degree of softening is required for optimal quality in fruit, over-softening is undesirable and is a sign of senescence or internal

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decay. The maintenance of textural quality is often critical in certain types of processing, for example in canning and freezing.

Flavor and aroma Flavor is a complex of taste and ………… components. Total flavor can rarely be assessed by the consumer prior to purchase but it is critical in the repeat purchase of a particular product or product cultivar. Key taste components in fresh produce are sweetness, acidity, astringency and bitterness. Aroma can be determined to some extent before purchase by the consumer but it tends to be important as a positive factor only in highly aromatic products such as certain cultivars of melons or mangoes. The aroma profile can change dramatically during the post-harvest life of fresh produce, particularly in climacteric fruits in which the dominant volatile may be quit different in the unripe fruit, the ripe fruit and the over-ripe or senescing fruit. An unexpected or unpleasant aroma may make a product unmarketable even if all other quality factors are quite acceptable. Therefore ………….can be an important factor in the storage and shelf-life of fresh produce.

TASK 10: MATCHING Match a word or phrase in A with its definition in B A Aroma

B A pleasant characteristic odor, as of a plant, spice, or food

Texture

A structure of interwoven fibers or other elements

Microorganism

An organism of microscopic or submicroscopic size, especially a bacterium or protozoan

Shelf-life

The length of time a product may be stored without becoming unsuitable for use or consumption

Hazardous

Marked by danger; perilous

Tissue

A fine, very thin fabric, such as gauze

Fiber

Something that provides substance or texture

Crop

Cultivated plants or agricultural produce, such as grain, vegetables, or fruit, considered as a group

Freeze

To pass from the liquid to the solid state by loss of heat

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Reading 3. Olive Oil: Treatments Like most vegetable oils, non-edible forms of olive oil are neutralized, bleached, and deodorized to obtain a bland fatty material which is usually blended with natural oil. The industrial process of refining should be considered as a means to restore a defective but still valuable product. Lampante oils usually have market prices higher than those of seed oils.

Factors such as acidity, peroxide value, and flavor score determine whether an oil is suitable for consumption or has to be refined. Each processing step has specific functions for removing certain major or minor constituents. Alkali refining removes free fatty acid, phospholipids, and pigments. In the presence of water, mucilage and resinous substances become insoluble and separable. Thus, the two treatments, neutralization and removal of mucilaginous substances, can take place at the same time. The elimination of mucilage is important because such substances reduce the capacity of activated earths and carbon used for bleaching. Bleaching reduces chlorophylls, carotenoids, and residual fatty acid salts. Deodorization removes volatiles, oxidation products, carotenoids, free fatty acids, pesticide residues and part of sterols, tocopherols, and hydrocarbon. Refining also destroys peroxides and thus the stability of the oil is increased. If the oil is winterized, waxes and removed. This additional step is necessary for olive oilresidue oil.

An ideal refining process aims to keep unchanged the structure of triacylglycerols an minimize configuration changes of fatty acids as well as looses of valuable constituents such as tocopherols. However, such losses are inevitable; therefore, the addition of alpha-tocopherol at a maximum level of 200 mg/kg to refined olive oil and olive-pomace oil is permitted by the International Olive Oil Council and the Codex Alimentarius to restore natural tocopherols lost in the refining process.

TASK 11: COMPREHENSION QUESTIONS Answer the questions below 1. What‘s phase of oil? .................................................................................................................................................................... 2. How to make consumer accept vegetable oil? .................................................................................................................................................................... 3. How to reduce oil‘s pigment? ....................................................................................................................................................................

TASK 12: TRUE OR FALSE Decide whether the following statements are true (T) or false (F).

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1. Palm oils have prices cheaper Olive oils ....................................................................................................................................................... 2. Neutralization uses alkali to remove free fatty acid, phospholipids and pigments .................................................................................................................................................................... 3. The refining olive oil just include triacylglycerols .................................................................................................................................................................... 4. Because of vitamin, olive oil‘s prices higher other vegetable oils .................................................................................................................................................................... TASK 13: GAP FILLING Complete the table below with appropriate words or phrases

Neutralization

acidity

silicas

deodorization

husk

neutralized

refining

peroxide

The first step of refining is (1)…..……….. of free fatty acids. Low acidity oils are easily treated by sodium hydroxide solution. Neutralization of high (2)……….oils, especially (3)………… oil, is more difficult. Oils (4)………….. by alkali are subjected to bleaching by earths and, if necessary, by activated carbon. Synthetic (5)…………can be used in combination with bleaching earths. If free acids are removed by physical (6)……………., the oil needs a pre-refining process. It is first degummed and bleached and then deacidified by (7)…………... Free fatty acids do not disturb the activity of decolorizing earths. Physical refining takes place in a stainless steel deodorizer where there is a vacuum of 0,1 mm of residual pressure, the temperature is approximately 230oC and there is a flow of direct steam. When the process is over, the oil has practically zero acidity and (8)………………value.

TASK 14: MATCHING Match a word or phrase in A with its definition in B Neutralization

A reaction between an acid and a base that yields a salt and water

Bleach

to make white or colorless

Deodorize

To mask or neutralize the odor of

Refine

purify

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Tocopherol

Any of a group of closely related, fat-soluble alcohols constituting vitamin E and similar compounds

Palm

A kind of tropical tree

Olive

A Mediterranean evergreen tree

Carotenoid

Any of a class of yellow to red pigments found especially in plants, algae, and photosynthetic bacteria

chlorophyll

Any of a group of green pigments that are found in the chloroplasts of plants

TASK 14: How to find good keywords Find the keywords in reading paragraphs 2&3. TASK 15: Summary In about 5 sentences, summarize the main idea in paragraphs 2&3.

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Part 4. Writing up Research, Scientific Paper Unit 30.

Writing up Research, Scientific Paper

Objective: After reading this unit, you should able to Know how to write a research, scientific report. Know how to write introduction. Know to write material and experimental. Know to write results and discussion. Know to write abstract.

As a science researcher, you are able to read and understand complex, high-level material in your field. However, you may find it difficult to produce written English which is at the same level as your reading. You may feel that your English writing does not represent the content of your work effectively or accurately. Developing the skills to write up your own research is the only way to join the international science community. If you depend on English speakers to translate your writing, their translation may not represent exactly what you intended. If you depend on proofreaders to correct your English they may not notice some errors, because a sentence which is grammatically correct is still ‗wrong‘ if it does not mean what you intended. Also, a proofreader may not check whether your writing fits the conventional ‗science research‘ patterns. For example, you may have forgotten to justify your choice of method or explain how your results relate to your original question, and this could mean that an editor of a science journal rejects your paper as unprofessional. Writing and publishing a research paper is the best way to get your career of the ground. If you can turn your thesis or research project into a useful paper, your CV (Curriculum Vitae) will immediately look more professional and will be more competitive internationally. You may feel that you don‘t have the time to improve your English, but you already know most of what you need from the reading you have done over the years.

The structure of a research article is presented in the order in which it appears in a paper/thesis so that you can trace the connections between each part and see the sequence in which information is presented to the reader. The first thing you may notice about Fig. 1 is that it is symmetrical. This is because many of the

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things you need to do in the introduction are done — in reverse order — in the discussion/conclusion. For example, you need to write an opening sentence which enables you and your reader to ‗get in‘ or start your paper/thesis and you also need to ‗get out‘ at the end of the discussion/conclusion by finding an acceptable way to end the paper/thesis. In addition, you must look for a way to interface with the central report section at the end of the introduction, and again — in reverse — when you move out of the central section to start the discussion/conclusion. Something else you should notice about the shape of the diagram is that it narrows towards the central report section, and widens after it. This is represents the way information is ordered in the introduction and the discussion/conclusion: in the introduction you start out by being fairly general and gradually narrow your focus, whereas the opposite is true in the discussion/conclusion.

1. How to write an introduction?

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You may want to start your introduction by describing the problem you are trying to solve, or the aim of your work. There are four language areas which are important in the introduction such as tense pairs (present simple/present continuous and past simple/present perfect), signaling language, passive/active use and paragraphing.

In term of signaling language, one of your tasks as a writer is to make sure that gap is closed, so that your reader is carried carefully from one piece of information to the next. Connecting sentences and concepts is good for you too, as it forces you to develop your ideas logically. One way to connect sentences is to overlap, meaning to repeat something from the previous sentence. Another way is to use a pronoun (it, they) or pro-form (this method, these systems) to glue the sentences together. The third way is not to finish the sentence at all, but to join it to the next sentence with a semicolon or a relative clause (a ‗which‘ clause). Joining sentences with a semicolon works well when two sentences are very closely related and one of them is quite short. The fourth way is to use a signalling sentence connector to indicate the relationship between one sentence and the next, or one part of a sentence and the next. You know how useful sentence connectors are from your reading; when you see a word like therefore or however, you are able to process the next piece of information in the sentence correctly even if you don‘t understand every word. This is because the sentence connector signals the function of the information in the sentence. The opposite is also true: when the writer does not signal the function of the information with a connector, it is harder for the reader to process the information. Even if the grammar is perfect and every word is correct, the reader still may not be sure what the information is doing and may interpret it differently from the way the writer intended. On the other hand, correct paragraphing is essential, but it is easy to get into poor paragraphing habits, either through laziness or carelessness. If you often write one-sentence paragraphs or your paragraphs seem to be very long or you‘re not sure when to start a new paragraph, you are making writing harder for yourself. When you are planning your paper, write down each idea/concept that you want to talk about, checking that they are in a logical order and then listing what you want to say about each, using bullet points. This will help you create paragraphs that have a logical and coherent structure.

2. How to write materials and methods?

It is sometimes called materials and methods, or it can be called procedure, experiments, methodology or model. This section is the first part of the central ‗report‘ section of the research article and it reports what you did and/or what you used.

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It is true that your work must contain sufficient detail to be repeatable, but the type of writing you will need to do is not just a record of what you did and/or used. One of the most interesting and important changes you need to make in the way you write is that until now, you have probably been writing for people who know more about your research topic than you do. You have been displaying to them that you understand the tasks they have set and have performed them correctly. However, when you write a research article, people will be learning from you. Therefore you now need to be able to communicate information about a new procedure, a new method, or a new approach so that everyone reading it can not only carry it out and obtain similar results, but also understand and accept your procedure. This section deals with three language areas which are important in the methodology: passives and tense pairs, use of ‗a‘ and ‗the‘, adverbs and adverb location. When you write about what you did and what you used, you need to be able to distinguish between standard procedures, i.e. what is normally done or how a piece of equipment is normally constructed, and what you did yourself. Uses the present simple tense to describe what is normally done or to describe a standard piece of equipment used in the research and uses the past simple tense to describe what you did yourself. It is conventional in this section to use the passive for both, and the agent of the action is not mentioned in the sentence — we don‘t add ‗by the researcher‘ or ‗by me‘ at the end.

We can streamline these so that our model has four basic components. Unlike the introduction model, in which all the items of each component are likely to be used, this is a ‗menu‘ from which you select items appropriate to your research topic. If there were no problems, you won‘t need the fourth component at all. 1. Provide a general introduction and overview of the materials/methods; restate the purpose of the work; give the source of materials/equipment used; supply essential background information 2. Provide specific and precise details about materials and methods (i.e. quantities, temperatures, duration, sequence, conditions, locations, sizes); justify choices made; indicate that appreciate care was taken 3. Relate materials/methods to ther studies 4. Indicate where problems occurred In order to complete the information you need to write this section of your paper you now need to find appropriate vocabulary for each part of the model

3. How to write the result?

In most cases, the results of your work can be given in graphs, tables, equations or images. Why, then, should you bother to write a results section? Why not simply provide good, clear graphs or tables with

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good, clear titles and perhaps a few notes underneath each? Thinking about these questions is a good way to begin to understand what you should be writing in this section. Almost everyone writes a results section, so it is clear that some things cannot be achieved by just using tables, graphs or other images of your results. They can be achieved only by using words. There are many reasons for writing a results section. In the first place, some of your results may be more interesting or significant than others, and it is difficult to communicate this in a table or graph. Also, it is essential to relate your results to the aim(s) of the research. Thirdly, in some cases you may want to offer background information to explain why a particular result occurred, or to compare your results with those of other researchers. In addition, your results may be problematic; perhaps some experiments were not fully successful and you want to suggest possible reasons for this. However, one of the most important reasons for writing a results section rather than relying on graphs, tables and other images is that you must communicate your own understanding and interpretation of the results to your readers. Results do not speak for themselves; if they did, the tables or graphs of your results would be enough. Your readers do not have to agree with you but they need to know your opinion and understanding of your results.

In order for other researchers to be able to repeat your work accurately and compare their results with yours, you need to be able to describe the order and time sequence of what you did and found in a very precise way. Time sequence means how long each step took and where it occurred in the sequence. You cannot use only then or next; these words tell your reader the order in which events occurred but they don‘t provide information about how long each event took, how soon the next event occurred or where it occurred in the sequence. A clear understanding of the time sequence will help your reader to picture it and repeat it for themselves.

It is also important to communicate clearly how often a particular event or result occurred. If a particular result occurred on every occasion a test was carried out, then it is a very reliable result; if it sometimes occurred when the test was carried out, that is a less reliable result. You can describe your results in numbers or percentages but those numbers or percentages are already visible to your reader in the graph or table; your reader needs to know what the numbers or quantities mean in order to understand them. For example, if the table or graph of your results shows that the effect you were looking for occurred in 23% of cases, you can communicate this as a strong result (in as many as 23% of cases) or a weak result (in only 23% of cases). Losing this opportunity to communicate what your results mean can cause problems. If you do not describe or comment on your results in words, the reader may perceive them differently from you. This will have a damaging effect on the rest of your paper, in particular on your conclusions. You want your readers to accept your conclusions, and those conclusions

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should follow logically and naturally from your results. If you do not comment on your results so that the reader can share your understanding of them, s/he may see them differently. As a result, the conclusion you eventually derive from those results will not seem either natural or logical; in fact it can even seem surprising or rather strange to the reader.

4. How to write discussion and conclusion?

Some journals end with a subsection titled discussion, some end with a subsection titled results and discussion and others end with a subsection titled conclusions. In the first two cases the elements which need to be included in the discussion are similar. Where there is a conclusions section, it is short, usually comprising one or two paragraphs focusing on specific aspects of the discussion. The graphic representation at the beginning of each unit is symmetrical because many of the elements of the introduction occur again in the discussion/conclusion in (approximately) reverse order. The introduction moves from a general, broad focus to the narrower ‗report‘ section of the paper, and the discussion/conclusion moves away from that narrow section to a wider, more general focus. The discussion looks back at the points made in the introduction on the basis of the information in the central report section.

When you started the introduction, you helped your readers move into the research article by establishing that the topic was a significant topic, providing background information and so on. Following the same pattern in reverse, you end the discussion/conclusion by helping your readers move out of the article. In the introduction, you wrote about the work of other researchers, creating a kind of research map for your readers so that they could see what type of work existed in this field; in the discussion/conclusion you locate your study in relation to that research map. You then went on in the introduction to locate a gap in the research or describe a problem associated with existing research; in the discussion/conclusion, you are expected to say to what extent you have responded to that gap or solved that problem. At the end of the introduction you wrote about the present paper, creating an interface with the content of your own work so that you could move the reader on to the central report section of your paper; in the discussion/conclusion, as we will see, it is common to begin by revisiting some aspect of your work, so as to create that interface in reverse and enable you to move away from the central report section.

5. How to write abstract?

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The abstract was printed at the top of a research article and its function was mainly to encourage the reader to continue reading the article and to facilitate that reading by providing a brief preview. The reader and the writer didn‘t consider the abstract of a research article as an independent unit because it was not normally read without reference to the article itself. Abstract databases allow scientists to search and scan the scientific literature and then decide which research articles they want to read in detail. Some readers simply want to know what is going on in their research area and may not be interested in the details; others may want to know details but are only interested in research articles which are directly relevant to their own research. However, if readers are going to actually read your research article, the abstract now needs to persuade them to obtain a copy of it, not just encourage them to keep reading a paper they have already accessed.

The content of the abstract is derived from the rest of the article, not the other way around. Although you should not simply cut and paste whole sentences from the body of the article, the abstract does not contain material which is not already in the paper. This means that you don‘t need to create completely new sentences; once you have decided what should go in the abstract you can select material, including parts of sentences and phrases, from the relevant sections of the paper and adapt or modify them to meet the demands of an abstract. This also means that the abstract is easier to write than the rest of the paper! The abstract usually has a strict word limit. Most are between 80–150 words and are written as a single paragraph. Even longer abstracts (150–250 words) are usually written as a single paragraph. The abstract is sometimes written in a slightly less technical way than the article itself in order to attract a wider audience.

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Unit 31.

Some Presentation Skills

Have you ever ask yourself about how to give effective professional and academic presentations? In this case, we talk more details about preparation the presentation and performing the presentation. Those are one of the most important parts which make the successful presentation. Please remember that ―In all things success depends on previous preparation, and without such preparation there is sure to be failure‖. There are five questions you should anwers in the stages of preparation such as why, who, what, how, where and when. Firstly, the general purpose of presentation is that showing the information and convincing people to believe what you say. Other purposes are telling the audience about new procedures, therefore and persuading the audience to use your service. Also, you need to identify audience profile such as who are they?, how many audiences are listening?, why are they coming?,What do they know about the subject, Why are they interested in the subject? What is their relationship to you? etc. In order to make those stages, you need to make the presentation outline. Moreover, the outline of presentation must be good organization so that you can improve your ideas and reduce your nervousness. Furthermore, your audience can remember and understand your presentation better. To be success of those purposes, you should make them interested your topic by showing the relationship between the subject to the audiences. In addition, you should give the purpose of your research/subject briefly so that your audience can imagine what you say later on. According to the middle of presentation, you just display 3 or 4 pointsand focus on those points. Not only are every idea summarized clearly but also signposts can be used in this case.

After finishing the body of presentation, the ending must be summarised the main points.

Especially, the brief informations must be connected to the audience.

On the other hand, there are two main ideas illustrate how to make the wonderful presentation such as key words. As you know, the role of key words is repeated in this presentation. It is very important for you to answer every question. Depending on keywords, you use index card to remind the main ideas you will talk in the oral presentation. Moreover, you should print in it captital so that you can see it clearly. Now, let‘s start to see how to perform the presentation effectively. Firstly, you should say hello to your audience. That is the most important key to connect you and your audiences. Then, you also say who you are even some audiences know you. After that, you must give the purpose and main points of your presentation. There are four things you should avoid when you present something such as jargon, complex phrase, being too formal and long sentences.

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We remind you that your presentation is not only the content but also the interested showing. So, you can use the stories which relate with your presentation. Besides, you can explain your ideas by using the analogy so that your audience can be active and excite your oral presentation and your content. In addition, visual aids and body language are also much more important. You shoul try to illustrate your contents by using the pictures. Finally, you should finish your presentation on time and make the conclusion of your presentation.

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Unit 32.

How to Avoid the Reviewer’s Axes Stephen D. Senturia Professor of Electrical Engineering Massachusetts Institute of Technology Cambridge, MA 02139 USA [email protected]

http://www-bsac.eecs.berkeley.edu/~muller/jmems.web/sds_editorial_june_2003.pdf

ABSTRACT Based on his many years of experience, a JMEMS editor provides ‗guidelines for authors‘ that will, if followed, greatly reduce the risk of a devastatingly negative result from the review process. The premise is that there are certain things that rightfully anger reviewers, and, once angered, the reviewers become both negative and aggressive in their judgments – hence, the imagery of ―the reviewer‘s axe‖ and how to avoid it. INTRODUCTION Since this is a personal commentary, I will use the first person, something that no proper writer of scientific discourse would ever do. As an author of many technical papers over my 35-year academic career, I have too often felt the anxiety of opening that envelope from the journal editor, which, from its bulk, obviously contains my precious manuscript, returned to me for either minor revision, massive rework, or – the ultimate wound – assignment to the manuscriptal trashbin. Now, having spent some 17 years on the opposite side of the table, my cumulative experience with many manuscripts and almost equally many unhappy authors is that the primary reason reviewers attack certain manuscripts is that those manuscripts are genuinely flawed. Many, if not most authors won‘t agree, at least not at first. So I thought it would be helpful to authors to set down some practical suggestions for preventing the reviewer‘s axe from giving the authors a whack.

A scientific manuscript is intended to communicate new information and to teach new material to a willing audience. Many authors forget this simple fact; rather, they view the writing process as an opportunity to bolster their own egos and impress the reader, even discomfit the reader somewhat, either with too much material or too little. Since there are many different styles of paper, I will select a

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hypothetical example of an experimental paper in which the authors make a minor advance in an established experimental method, and they then use this method to obtain some new results that are to be compared with a model that is also a minor modification of already published work. Along the way, some unusual behavior is observed that the modified model cannot explain. The authors believe that they understand why this behavior is observed, and wish to propose their explanation, even though they have not yet done the definitive experiments to prove their hypothesis.

SENTURIA’S GUIDELINES

How should the authors think about organizing and writing this paper? I propose a set of simple guidelines. The names are listed below, followed by some discussion in which each guideline is explored in depth:

(Almost) Nothing is New. Rely on the Believability Index. Watch for Gambling Words. Don‘t Be a Longfellow. Don‘t Pull Rabbits Out of Hats. Mine All the Gold Remember: Reviewers are Inarticulate and Authors are (somewhat) Paranoid

Violation of one or more of the principles explained under each guideline risks getting the reviewer angry (with cause), and once that happens, the axe comes out and swings with purpose. I don‘t believe that a manuscript has ever been written that cannot be improved, but an angry reviewer finds many more faults than a reviewer who believes that the author has basically done a highly professional job, both of research and of writing. It‘s just plain dumb to aggravate a reviewer. Every author‘s goal should be to keep the reviewer‘s axe in its sheath.

(Almost) Nothing is New

Everyone knows that there is nothing new under the sun. Everyone, that is, except an ambitious author who believes that his or her work is unique. While there are a few truly unique and amazing results published once in a while, most of our work is built on the work of others. 219

It is every author‘s obligation to establish clearly the context in which the new work belongs, both by a brief introduction and by the citation of appropriate references (which the author should have read, not simply copied from someone else‘s reference list). If an author doesn‘t know any relevant references, then he or she should get on-line and find them – they are there! I used to tell my graduate students: ―First, figure out what you have done. Then, go to the library and find it!‖ They might not find exactly what they themselves had done, but they would find all kinds of relevant material that needed to be sifted to find the critical subset that was so relevant that it demanded citation.

Along the way, there are some additional principles to follow:

If you have a manuscript on a closely related topic that is either buried in some conference digest, is still in review, or has already been accepted by a journal but is not yet in print, it is your obligation both to notify the editor and reviewers of the existence of this paper and provide prepublication copies to aid the review process. This is perhaps the single most significant source of reviewer venom – the discovery of a related paper that the authors have kept hidden from the reviewers. And the venom is real – the reviewer feels that the author is trying to trick the review process, so out comes the axe.

If a reference is relevant enough to your work to cite it, then it is also relevant to your results. Many authors provide a cosmetic list of references at the beginning of a paper but never return to compare their allegedly new results with the contents of the cited papers.

This infuriates

reviewers, and rightly so. Scientific advances are the result of confirmation and comparison among many independent investigators. When results are presented without any comparisons to prior work, reviewers get angry, and they get out the axe.

Rely on the Believability Index.

The essence of scientific advance is that results are believable because they have been repeated and checked by independent investigators.

By definition then, a truly new result is not 220

scientifically confirmed until it has been repeated by others. This leads me to the concept of a Believability Index.

In creating an outline for this hypothetical experimental paper with modest advances both in experimental method and in the model and with some surprising results that come out, the author should think about the believability of the various constituents of the outline. Clearly, the existence of a cited public record of previously published work (regardless of whether that work is or is not correct) is highly believable. So are the basic laws of physics, well-established theories and models, and widely practiced experimental procedures. All of these have a high believability. In contrast, any new result has a lower believability. If a result hasn‘t been confirmed by others, it is not ―established‖ and therefore is intrinsically less believable than a peer-confirmed result. At the lowest level of believability is an author‘s speculation as to the reason for any new result. (Said another way, ―Talk is cheap.‖) But if a new experimental result is sufficiently documented in a manuscript, reviewers may accept it, even if they don‘t agree with the speculative explanation for the new behavior. All of this leads to the principle of the Believability Index, which automatically assigns an order to the contents of the paper:

Write the paper in order of decreasing believability.

The beauty of this approach should be self-evident. If a paper is written in order of decreasing believability, each reader will be led to agree with what is stated at the beginning, because it has high believability, but later might balk at accepting either a new experimental result (if improperly explained) or a speculative explanation. A properly ordered paper will have NO critical high-believability content after the introduction of the first moderate- or low-believability material. And the reader who, at some point along the way, fails to agree with the author, has the benefit of knowing all of the high-believability material at the point of disagreement and thus can focus the disagreement on the right issues.

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Sample-preparation methods, which are assumed to be completely factual reports of what an author did, should have a high believability and thus belong early in a paper. A common mistake of authors is to surprise readers relatively late in a paper, well beyond the first low-believability point, with a report of some new sample preparations and the like. That kind of writing makes for choppy papers that are hard to read, and hard-to-read papers irritate reviewers.

If you are reporting a new experimental procedure, in order to keep its believability high, you should trace by example how you go from raw data to reduced data to extracted measured result, and mention such things as calibration (if not based on a commercial instrument specification), the number of samples, and the relation between the error bars on the graph and your data (is it full range? probable error of the mean? what?). Confirmation that the new method gives an expected answer in a well-known case is an obvious believability-builder. This helps to improve the believability of your new experimental results, which was presumably the whole point of writing the paper in the first place.

If you are reporting a new model, you need to anchor the model in high-believability starting points, then make clear when you are jumping off the believability cliff by making an assumption that is not provably correct.

As to whether models or experimental methods go first is largely a matter of taste. If there are new components to both, then be careful of going too far down one road or the other in terms of believability before introducing the other.

The loveliest outcome of this approach is that you, as author, are led to place all speculation after the point at which all more moderate-believability things such as new experimental results are already in hand. This sometimes poses difficulties for authors. The tendency is to dribble out results, then comment (see ―Longfellow‖ below), then dribble out some more results, and so on. Get the higher-believability material on record before speculating. Your reviewer will love you.

Watch for Gambling Words.

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You are probably wondering why I would be interested in gambling words in this context. For this insight, I am indebted to Prof. Arthur C. Smith of MIT who, when co- 4Senturia – How to Avoid the Reviewer‘s Axe JMEMS Editorial, June 2003 authoring a paper with me back in the early 70‘s, cautioned me against using what he called ―gambling words‖ like ―obviously,‖ ―probably,‖ ―certainly,‖ and ―undoubtedly.‖ Art‘s comment was that if you have to persuade using probabilistic words, it means you can‘t prove your point and you are speculating. Hence: If you find yourself inclined to use gambling words, it means you don‘t know what you are talking about, and, therefore, such material has, intrinsically, low believability. Replace the gambling words with words that make it clear that you are speculating, and place such comments in the appropriate place in the paper, along with other low-believability speculations. Don’t Be a Longfellow

In Tales of a Wayside Inn, the poet Longfellow presents a set of stories told by various guests at the inn, sitting around the fire. While Longfellow was a wonderful story-teller, he should NOT be adopted as the role model for scientific writing. It is an alluring temptation to state a fact and then tell a story explaining this fact, then give another fact and tell another story, on and on until one runs out of new facts. (For some reason, chemists, in particular, seem to love this model.) What‘s wrong with it is that it violates the rule of decreasing believability. Stories are nice, but might, like Longfellow‘s, be fiction. Scientific writing, one hopes, is non-fiction. Resist the temptation to be a modern-day Longfellow until ALL of the high-believability material has been presented and one is ready to telegraph the fact that one is speculating by using headings such as ―Discussion‖ or ―Interpretation.‖ Don’t Pull Rabbits Out of Hats

We all recall the thrill when, as children, seated on the floor of a crowded school auditorium, we would see the visiting magician pull a rabbit out of his hat. Some of that thrill seems to stick, because many scientific writers seem to want to imitate the magician. They store up a confirming experiment until after they have led their readers down a particular garden path, and then, and only then, do they reveal that they did this extra experiment that (the authors hope) proves their 223

point. There are two problems with this: First, it clearly violates the Believability-Index rule by placing (presumably) high-believability material after some lower-believability explanations of earlier results. Second, it opens the possibility that there is really a flaw in the reasoning. Reviewers get tenacious searching for the flaws when confronted with rabbits out of hats. The rule is simple: Don‘t do it.

Mine All the Gold

Imagine that you have hiked up a desolate canyon in mountainous country, took a few shovelfuls of promising-looking dirt, dumped them in the gold pan and, in the nearby stream, washed it down until you found a few nuggets of gold. You are elated, and decide to rush to the nearest mining office and stake a claim. Then, inexplicably, you announce your claim to the world but never return to mine the gold.

Everyone would think you a fool if you were to do this. But, in reality, many scientific writers, in effect, fail to ―mine the gold.‖ It costs real time and effort (and often significant sums of hard-toget money) to get good data. The data represent the shovelfuls of earth that yield a few nuggets. The analog of ―staking the claim‖ is writing a paper – it is through this process that you announce to the world that ―there is gold around.‖

Given the cost of those data, however, it would be

foolish not to try to get every single nugget out of the dirt, or, at a minimum, every nugget out of the shovelfuls of dirt you have already collected.

Many authors, regrettably, in my opinion, are too quick to give up on what they can learn from data. (This is the opposite of over-speculation on what poorly supported results mean – that is a different sin which was covered under the general ―Believability‖ heading.) While it may not be essential to the publication of the nuggets you did find, your chances of success with reviewers goes way up when you are able to demonstrate a DEEP understanding of what your data do and do not show. For example, many authors look at the signal they are able to measure and fail to note that the noise spectrum may provide information on fundamental processes that might limit detectability. Other authors fail to search for correlations buried in their results that give hints of things that may be new or important. In short, be tenacious. Try to mine all of the information 224

from data, even if it pushes you in the direction of speculation and other low-believability comments. As long as such comments are clearly labeled as speculative and are potentially interesting, reviewers will applaud both the diligence and the forthrightness.

Remember: Reviewers are Inarticulate and authors are (somewhat) paranoid I close this article with guidelines on how to deal with the reviewers‘ comments, once they have been received:

When a reviewer complains about something in a paper, the chances are very good that there is a problem with the paper. Not every comment by every reviewer is a correct or proper criticism, but I would say that more than 90% of the criticisms that I have seen have some degree of merit.

But, reviewers are inarticulate. Reviewers often state their objections badly, and that makes their reviews look arbitrary, even whimsical. The authors‘ anger and paranoia are then provoked. Now what?

As an author, it is your obligation to respond to each and every reviewer criticism. The manner with which you do this has a great effect on the smoothness of the road to publication. If you try, as some have, to bully the reviewer (or the editor) into submission without making a constructive response, both the reviewer (and probably the editor) will do the equivalent of tossing you out on the street. I have seen cases in which brilliantly written polemics from angry authors that effectively rebut a reviewers‘ point failed in their goal because the authors wouldn‘t incorporate the essence of their rebuttal into suitable modifications of their precious manuscript.

Ego

interferes with constructive action, and paranoia cripples it.

Asserting scientific correctness of your own work is a task to be undertaken with some humility and with respect for the established knowledge that has preceded your work. Difficult as it may be, hold your temper and your polemics when you get a review, and try instead to think ―why is the reviewer really bothered at this point?‖ If you, as author, can figure out why the reviewer was led to a particular comment, you will find a pathway to improving the paper and satisfying 225

the reviewer at the same time. Often, the failing of the paper is not at the precise point raised by the reviewer but rather arises somewhere else, such as through a non-optimal order of topics or comments, or an omitted few words of explanation elsewhere else in the paper. A remarkably open mind is required to read reviewers‘ criticisms in this vein, but it is vastly productive and greatly shortens the time to publication. Of course, some reviewers‘ comments are simply wrong. If you handle the proper comments with courtesy and professionalism, the editor is much more likely to agree with you about the comments that you reject. So, my advice is to submit a complete restatement of the reviewer comments with your own comments added on how you have responded to each and every criticism. If you do a good enough job on this, the editor may find that he or she can make a publication decision without going back through the review process, saving many weeks in publication time. And the reputation you develop by being mindful of the realities of referee inarticulateness will serve you well throughout your career.

And, next time, you will write a better paper.

Stephen D. Senturia Brookline, Massachusetts February 22, 2003

“Now this is not the end. It is not even the beginning of the end. But it is, perhaps, the end of the beginning.” Sir Winston Churchill, Speech in November 1942 British politician (1874 - 1965)

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